#logging

---

In the diverse and ever-evolving JavaScript ecosystem, logging remains a critical component for development, debugging, and monitoring applications. While numerous logging libraries exist, LogTape stands out with its unique combination of simplicity, flexibility, and cross-runtime compatibility. Let's explore why LogTape deserves consideration for your next JavaScript or TypeScript project—whether you're building an application or a library.

Zero Dependencies: A Lightweight Footprint

One of LogTape's most compelling features is its complete absence of dependencies. In an era where “dependency hell” plagues many JavaScript projects, LogTape offers a refreshing alternative:

// No additional packages to install beyond LogTape itself
import { configure, getConsoleSink, getLogger } from "@logtape/logtape";

This zero-dependency approach provides several advantages:

Reduced bundle size

No transitive dependencies means smaller packages

Enhanced stability

No risk of breaking changes from upstream dependencies

Simplified security

Fewer potential vulnerabilities from third-party code

Lower integration overhead

Particularly valuable for library authors who don't want to burden users with additional dependencies

Runtime Diversity: Write Once, Log Everywhere

While many popular logging libraries focus primarily on Node.js, LogTape provides seamless support across diverse JavaScript runtimes:

• Node.js
• Deno
• Bun
• Web browsers
• Edge functions (e.g., Cloudflare Workers)

This runtime flexibility means you can use consistent logging patterns regardless of your deployment environment:

// Same API works seamlessly across all JavaScript runtimes
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-service", "user-management"]);

// Works in Node.js, Deno, Bun, browsers, or edge functions
logger.info`User ${userId} logged in successfully`;

For teams working across multiple platforms or projects transitioning between runtimes, this consistency is invaluable. No need to learn different logging libraries or approaches—LogTape works the same way everywhere.

Hierarchical Categories: Fine-Grained Control

LogTape's hierarchical category system represents a standout feature that's surprisingly rare among JavaScript logging libraries. Categories allow you to organize logs in a tree-like structure:

// Parent category
const appLogger = getLogger(["my-app"]);

// Child category inherits settings from parent
const dbLogger = getLogger(["my-app", "database"]);

// Grandchild category
const queryLogger = getLogger(["my-app", "database", "queries"]);

// Alternative approach using getChild()
const userLogger = appLogger.getChild("users");
const authLogger = userLogger.getChild("auth");

This hierarchical approach offers powerful benefits:

Targeted filtering

Configure different log levels for different parts of your application

Inheritance

Child loggers inherit settings from parents, reducing configuration overhead

Organizational clarity

Logs naturally follow your application's module structure

Here's how you might configure logging levels for different categories:

await configure({
  sinks: {
    console: getConsoleSink(),
    file: getFileSink("app.log"),
  },
  loggers: [
    // Base configuration for all app logs
    { 
      category: ["my-app"], 
      lowestLevel: "info", 
      sinks: ["console", "file"] 
    },
    // More verbose logging just for database components
    { 
      category: ["my-app", "database"], 
      lowestLevel: "debug", 
      sinks: ["file"] 
    }
  ]
});

With this configuration, all application logs at "info" level and above go to both console and file, while database-specific logs include more detailed "debug" level information, but only in the log file.

Structured Logging: Beyond Simple Text

Modern logging goes beyond simple text strings. LogTape embraces structured logging, which treats log entries as data objects rather than plain text:

logger.info("User logged in", {
  userId: 123456,
  username: "johndoe",
  loginTime: new Date(),
  ipAddress: "192.168.1.1"
});

LogTape also supports placeholders in messages, connecting structured data with human-readable text:

logger.info("User {username} (ID: {userId}) logged in from {ipAddress}", {
  userId: 123456,
  username: "johndoe",
  ipAddress: "192.168.1.1"
});

Structured logging offers substantial benefits:

Improved searchability

Search for specific field values instead of parsing text

Better analysis

Perform data analysis on structured fields

Consistent format

Enforce standardized log formats

Machine-readable

Easier processing by log management systems

For performance-conscious applications, LogTape offers lazy evaluation of structured data:

logger.debug("Performance metrics", () => ({
  memoryUsage: process.memoryUsage(),
  cpuUsage: process.cpuUsage(),
  timestamp: performance.now()
}));

The function is only evaluated if the debug level is enabled, preventing unnecessary computation for suppressed log levels.

Extremely Simple Sinks and Filters: Minimal Boilerplate

LogTape's approach to extensibility is remarkably straightforward. Creating custom sinks (output destinations) and filters requires minimal boilerplate code.

Dead Simple Sinks

A sink in LogTape is just a function that receives a log record:

// Creating a custom sink is as simple as defining a function
const mySink = (record) => {
  const timestamp = new Date(record.timestamp).toISOString();
  const level = record.level.toUpperCase();
  const category = record.category.join('.');
  
  // Send to your custom destination
  myCustomLogService.send({
    time: timestamp,
    priority: level,
    component: category,
    message: record.message,
    ...record.properties
  });
};

// Use your custom sink in configuration
await configure({
  sinks: {
    console: getConsoleSink(),
    custom: mySink
  },
  loggers: [
    { category: ["my-app"], sinks: ["console", "custom"] }
  ]
});

Compare this with other libraries that require extending classes, implementing multiple methods, or following specific patterns. LogTape's approach is refreshingly straightforward.

Simple Filters

Similarly, filters in LogTape are just functions that return a Boolean:

// Filter that only passes high-priority or specific component logs
const importantLogsFilter = (record) => {
  // Always include errors
  if (record.level === "error" || record.level === "fatal") {
    return true;
  }
  
  // Always include payment-related logs
  if (record.category.includes("payments")) {
    return true;
  }
  
  // Filter out other logs
  return false;
};

await configure({
  // ...sinks configuration
  filters: {
    important: importantLogsFilter
  },
  loggers: [
    { 
      category: ["my-app"], 
      sinks: ["alertSystem"], 
      filters: ["important"] 
    }
  ]
});

LogTape also provides a convenient shorthand for level-based filtering:

await configure({
  // ...sinks configuration
  filters: {
    // This creates a filter for "warning" level and above
    warningAndAbove: "warning"
  },
  loggers: [
    { 
      category: ["my-app"], 
      sinks: ["console"], 
      filters: ["warningAndAbove"] 
    }
  ]
});

Perfect for Library Authors

LogTape is uniquely well-suited for library authors who want to incorporate logging without burdening their users. The core philosophy is simple:

1. Libraries provide logging output points
2. Applications configure how those logs are handled

Here's how a library might implement LogTape:

// my-awesome-lib/database.js
import { getLogger } from "@logtape/logtape";

export class Database {
  private logger = getLogger(["my-awesome-lib", "database"]);

  constructor(host, port, user) {
    this.host = host;
    this.port = port;
    this.user = user;
  }

  connect() {
    this.logger.info("Connecting to database", {
      host: this.host,
      port: this.port,
      user: this.user
    });
    
    // Connection logic...
    
    this.logger.debug("Connection established");
  }
  
  query(sql) {
    this.logger.debug("Executing query", { sql });
    // Query logic...
  }
}

The key point is that the library never calls configure(). Instead, it provides useful log output points with appropriate levels and contextual data.

Applications using the library can then decide exactly how to handle these logs:

// Application code
import { configure, getConsoleSink } from "@logtape/logtape";
import { Database } from "my-awesome-lib";

// Configure how logs should be handled
await configure({
  sinks: {
    console: getConsoleSink(),
    file: getFileSink("app.log")
  },
  loggers: [
    // Handle all library logs
    { 
      category: ["my-awesome-lib"], 
      lowestLevel: "info", 
      sinks: ["file"] 
    },
    // More verbose for database component during development
    { 
      category: ["my-awesome-lib", "database"], 
      lowestLevel: "debug", 
      sinks: ["console", "file"] 
    }
  ]
});

// Use the library
const db = new Database("localhost", 5432, "user");
db.connect();

This separation of concerns offers several benefits:

1. Library users have complete control over log handling
2. Libraries can provide rich logging without imposing implementation details
3. No risk of conflict with application logging configurations
4. Libraries can be "noisy" internally while allowing applications to filter as needed

Contexts for Richer Logging

LogTape provides context mechanisms for adding consistent properties across multiple log messages. This is particularly valuable for tracing requests through a system:

Explicit Contexts

const logger = getLogger(["my-app", "api"]);

// Create a logger with context
const requestLogger = logger.with({
  requestId: "abc-123",
  userId: 42,
  endpoint: "/users"
});

// All logs from this logger include the context properties
requestLogger.info("Processing request");
requestLogger.debug("Validating input");
requestLogger.info("Request completed", { durationMs: 120 });

Implicit Contexts (v0.7.0+)

For cases where you want context to apply across function calls without explicit passing:

import { getLogger, withContext } from "@logtape/logtape";

function handleRequest(req, res) {
  withContext({ 
    requestId: req.id, 
    userId: req.user?.id 
  }, () => {
    // All logs within this function and any functions it calls
    // will automatically include the context properties
    processRequest(req, res);
  });
}

function processRequest(req, res) {
  // No need to pass context - it's automatically available
  getLogger(["my-app", "processor"]).info("Processing data");
  
  // Call other functions that will also inherit the context
  validateInput(req.body);
}

function validateInput(data) {
  // This log also gets the requestId and userId
  getLogger(["my-app", "validator"]).debug("Validating input", { data });
}

This implicit context capability is invaluable for tracing requests through multiple layers of code without manually threading context through every function call.

When LogTape Might Not Be Your Best Choice

While LogTape offers compelling advantages for many use cases, it's not universally the best choice:

Extreme performance requirements

If your application logs tens of thousands of entries per second and raw performance is the top priority, specialized high-performance libraries like Pino may be more suitable with their focus on optimized logging throughput.

Extensive pre-built integrations

If you need immediate integration with numerous specific systems (Elasticsearch, Graylog, etc.) without writing any custom code, Winston's rich ecosystem of transports might provide a faster starting point.

Legacy systems with specific logging requirements

If you're maintaining systems built around specific logging patterns from Java or other environments, purpose-built libraries like Log4js might offer more familiar APIs.

Web browser-only applications with minimal logging needs

For extremely simple web browser-only logging needs where you just want basic console output with levels, even simpler libraries like loglevel might be sufficient.

Conclusion

LogTape stands out in the crowded JavaScript logging landscape by offering a unique combination of features that address real-world development challenges:

• Zero dependencies for a lightweight, secure foundation
• Runtime diversity supporting Node.js, Deno, Bun, browsers, and edge functions
• Hierarchical categories for better log organization and filtering
• Structured logging for improved analysis and searchability
• Simple extension mechanisms with minimal boilerplate
• Library-friendly design that respects separation of concerns

Whether you're building applications or libraries, working across multiple JavaScript runtimes, or simply seeking a clean, well-designed logging solution, LogTape deserves serious consideration. Its thoughtful design balances simplicity with powerful features, avoiding common pitfalls of JavaScript logging libraries.

For more information and detailed documentation, visit LogTape's official website.

---

Building a JavaScript library is a delicate balance. You want to provide useful functionality while being respectful of your users' choices and constraints. When it comes to logging—something many libraries need for debugging, monitoring, and user support—this balance becomes particularly challenging.

The JavaScript ecosystem has evolved various approaches to this challenge, each with its own trade-offs. LogTape offers a different path, one that's specifically designed with library authors in mind.

The current state of library logging

If you've built libraries before, you've probably encountered the logging dilemma. Your library would benefit from logging—perhaps to help users debug integration issues, trace internal state changes, or provide insights into performance bottlenecks. But how do you add this capability responsibly?

Currently, popular libraries handle this challenge in several ways:

The debug approach

Libraries like Express and Socket.IO use the lightweight debug package, which allows users to enable logging through environment variables (DEBUG=express:*). This works well but creates a separate logging system that doesn't integrate with users' existing logging infrastructure.

Custom logging systems

Libraries like Mongoose and Prisma have built their own logging mechanisms. Mongoose offers mongoose.set('debug', true) while Prisma uses its own logging configuration. These approaches work, but each library creates its own logging API that users must learn separately.

Application-focused libraries

winston, Pino, and Bunyan are powerful logging solutions, but they're primarily designed for applications rather than libraries. Using them in a library means imposing significant dependencies and potentially conflicting with users' existing logging choices.

No logging at all

Many library authors avoid the complexity entirely, leaving their libraries silent and making debugging more challenging for everyone involved.

Dependency injection

Some libraries adopt a more sophisticated approach by accepting a logger instance from the application through their configuration or constructor parameters. This maintains clean separation of concerns and allows libraries to use whatever logging system the application has chosen. However, this pattern requires more complex APIs and places additional burden on library users to understand and configure logging dependencies.

Each approach represents a reasonable solution to a genuine problem, but none fully addresses the core tension: how do you provide valuable diagnostic capabilities without imposing choices on your users?

The fragmentation problem

There's another challenge that emerges when libraries each solve logging in their own way: fragmentation. Consider a typical Node.js application that might use Express for the web framework, Socket.IO for real-time communication, Axios for HTTP requests, Mongoose for database access, and several other specialized libraries.

Each library potentially has its own logging approach:

• Express uses DEBUG=express:*
• Socket.IO uses DEBUG=socket.io:*
• Mongoose uses mongoose.set('debug', true)
• Axios might use axios-logger or similar packages
• Redis clients have their own debug configurations
• Authentication libraries often include their own logging mechanisms

From an application developer's perspective, this creates a management challenge. They must learn and configure multiple different logging systems, each with its own syntax, capabilities, and quirks. Logs are scattered across different outputs with inconsistent formats, making it difficult to get a unified view of what's happening in their application.

The lack of integration also means that powerful features like structured logging, log correlation, and centralized log management become much harder to implement consistently across all the libraries in use.

LogTape's approach

LogTape attempts to address these challenges with what might be called a “library-first design.” The core principle is simple but potentially powerful: if logging isn't configured, nothing happens. No output, no errors, no side effects—just complete transparency.

This approach allows you to add comprehensive logging to your library without any impact on users who don't want it. When a user imports your library and runs their code, LogTape's logging calls are essentially no-ops until someone explicitly configures logging. Users who want insights into your library's behavior can opt in; those who don't are completely unaffected.

More importantly, when users do choose to configure logging, all LogTape-enabled libraries can be managed through a single, unified configuration system. This means one consistent API, one log format, and one destination for all library logs while still allowing fine-grained control over what gets logged from which libraries.

// In your library code - completely safe to include
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-awesome-lib", "database"]);

export function connectToDatabase(config) {
  logger.debug("Attempting database connection", { config });
  // ... your logic
  logger.info("Database connection established");
}

The dependency consideration

Modern JavaScript development involves careful consideration of dependencies. While popular logging libraries like winston and Pino are well-maintained and widely trusted, they do come with their own dependency trees. winston, for example, includes 17 dependencies, while Pino includes 1.

For library authors, this creates a consideration: every dependency you add becomes a dependency for your users, whether they want it or not. This isn't necessarily problematic (many excellent libraries have dependencies), but it does represent a choice you're making on behalf of your users.

LogTape takes a different approach with zero dependencies. This isn't just a philosophical choice—it has practical implications for your library's users. They won't see additional packages in their node_modules, won't need to worry about supply chain considerations for logging-related dependencies, and won't face potential version conflicts between your logging choice and theirs.

At just 5.3KB minified and gzipped, LogTape adds minimal weight to their bundles. The installation process becomes faster, the dependency tree stays cleaner, and security audits remain focused on the dependencies that directly serve your library's core functionality.

Breaking the compatibility chain

Here's a challenge that might be familiar: you want your library to support both ESM and CommonJS environments. Perhaps some of your users are working with legacy Node.js projects that rely on CommonJS, while others are using modern ESM setups or building for browsers.

The challenge becomes apparent when you have dependencies. While ESM modules can import CommonJS modules without issues, the reverse isn't true—CommonJS modules cannot require ESM-only packages (at least not until the experimental features in Node.js 22+ become stable). This creates an asymmetric compatibility constraint.

If your library depends on any ESM-only packages, your library effectively becomes ESM-only as well, since CommonJS environments won't be able to use it. This means that even one ESM-only dependency in your chain can prevent you from supporting CommonJS users.

LogTape supports both ESM and CommonJS completely, meaning it won't be the weak link that forces this limitation. Whether your users are working with legacy Node.js projects, cutting-edge ESM applications, or hybrid environments, LogTape adapts seamlessly to their setup.

More importantly, when LogTape provides native ESM support (rather than just being importable as CommonJS), it enables tree shaking in modern bundlers. Tree shaking allows bundlers to eliminate unused code during the build process, but it requires the static import/export structure that only ESM provides. While CommonJS modules can be imported into ESM projects, they're often treated as opaque blocks that can't be optimized, potentially including unused code in the final bundle.

For a logging library that aims to have minimal impact, this optimization capability can be meaningful, especially for applications where bundle size matters.

Universal runtime support

The JavaScript ecosystem spans an impressive range of runtime environments today. Your library might run in Node.js servers, Deno scripts, Bun applications, web browsers, or edge functions. LogTape works identically across all of these environments without requiring polyfills, compatibility layers, or runtime-specific code.

This universality means you can focus on your library's core functionality rather than worrying about whether your logging choice will work in every environment your users might encounter. Whether someone imports your library into a Cloudflare Worker, a Next.js application, or a Deno CLI tool, the logging behavior remains consistent and reliable.

Performance without compromise

One concern library authors often have about logging is performance impact. What if your users import your library into a high-performance application? What if they're running in a memory-constrained environment?

LogTape addresses this with remarkable efficiency when logging is disabled. The overhead of an unconfigured LogTape call is virtually zero—among the lowest of any logging solution available. This means you can add detailed logging throughout your library for development and debugging purposes without worrying about performance impact on users who don't enable it.

When logging is enabled, LogTape consistently outperforms other libraries, particularly for console output—often the most common logging destination during development.

Avoiding namespace collisions

Libraries sharing the same application can create logging chaos when they all output to the same namespace. LogTape's hierarchical category system elegantly solves this by encouraging libraries to use their own namespaces.

Your library might use categories like ["my-awesome-lib", "database"] or ["my-awesome-lib", "validation"], ensuring that your logs are clearly separated from other libraries and the main application. Users who configure LogTape can then control logging levels independently for different libraries and different components within those libraries.

Developer experience that just works

LogTape is built with TypeScript from the ground up, meaning your TypeScript-based library gets full type safety without additional dependencies or type packages. The API feels natural and modern, supporting both template literals and structured logging patterns that integrate well with contemporary JavaScript development practices.

// Template literal style - feels natural
logger.info`User ${userId} performed action ${action}`;

// Structured logging - great for monitoring
logger.info("User action completed", { userId, action, duration });

Practical integration

Actually using LogTape in your library is refreshingly straightforward. You simply import the logger, create appropriately namespaced categories, and log where it makes sense. No configuration, no setup, no complex initialization sequences.

import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-lib", "api"]);

export async function fetchUserData(userId) {
  logger.debug("Fetching user data", { userId });
  
  try {
    const response = await api.get(`/users/${userId}`);
    logger.info("User data retrieved successfully", { 
      userId, 
      status: response.status 
    });
    return response.data;
  } catch (error) {
    logger.error("Failed to fetch user data", { userId, error });
    throw error;
  }
}

For users who want to see these logs, configuration is equally simple:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: ["my-lib"], lowestLevel: "info", sinks: ["console"] }
  ]
});

Bridging the transition

If your potential users are already invested in other logging systems, LogTape provides adapters for popular libraries like winston and Pino. This allows LogTape-enabled libraries to integrate with existing logging infrastructure, routing their logs through whatever system applications are already using.

The existence of these adapters reveals an honest truth: LogTape isn't yet a widely-adopted standard in the JavaScript ecosystem. Most applications are still built around established logging libraries, and asking users to completely restructure their logging approach would be unrealistic. The adapters represent a practical compromise—they allow library authors to take advantage of LogTape's library-friendly design while respecting users' existing investments and preferences.

This approach reduces friction for adoption while still providing library authors with a modern, zero-dependency logging API. Perhaps over time, as more libraries adopt this pattern and more developers experience its benefits, the need for such adapters might diminish. But for now, they serve as a pragmatic bridge between LogTape's vision and the current reality of the ecosystem.

A choice worth considering

Ultimately, choosing LogTape for your library represents a particular philosophy about the relationship between libraries and applications. It's about providing capabilities while preserving choice, offering insights while avoiding imposition.

The traditional approaches—whether using debug packages, application-focused loggers, or custom solutions—each have their merits and have served the community well. LogTape simply offers another option: one designed specifically for the unique position libraries occupy in the JavaScript ecosystem.

For library authors, this approach might offer several practical benefits. Your library gets detailed logging for development, debugging, and user support, while your users retain complete autonomy over whether and how to use those capabilities.

The broader benefit might be a more cohesive logging experience across the JavaScript ecosystem—one where libraries can provide rich diagnostic information that integrates seamlessly with whatever logging strategy applications choose to employ.

In a world where every dependency decision has implications, LogTape offers an approach worth considering: a way to enhance your library's capabilities while respecting your users' preferences and existing choices.

---

Building a JavaScript library is a delicate balance. You want to provide useful functionality while being respectful of your users' choices and constraints. When it comes to logging—something many libraries need for debugging, monitoring, and user support—this balance becomes particularly challenging.

The JavaScript ecosystem has evolved various approaches to this challenge, each with its own trade-offs. LogTape offers a different path, one that's specifically designed with library authors in mind.

The current state of library logging

If you've built libraries before, you've probably encountered the logging dilemma. Your library would benefit from logging—perhaps to help users debug integration issues, trace internal state changes, or provide insights into performance bottlenecks. But how do you add this capability responsibly?

Currently, popular libraries handle this challenge in several ways:

The debug approach

Libraries like Express and Socket.IO use the lightweight debug package, which allows users to enable logging through environment variables (DEBUG=express:*). This works well but creates a separate logging system that doesn't integrate with users' existing logging infrastructure.

Custom logging systems

Libraries like Mongoose and Prisma have built their own logging mechanisms. Mongoose offers mongoose.set('debug', true) while Prisma uses its own logging configuration. These approaches work, but each library creates its own logging API that users must learn separately.

Application-focused libraries

winston, Pino, and Bunyan are powerful logging solutions, but they're primarily designed for applications rather than libraries. Using them in a library means imposing significant dependencies and potentially conflicting with users' existing logging choices.

No logging at all

Many library authors avoid the complexity entirely, leaving their libraries silent and making debugging more challenging for everyone involved.

Dependency injection

Some libraries adopt a more sophisticated approach by accepting a logger instance from the application through their configuration or constructor parameters. This maintains clean separation of concerns and allows libraries to use whatever logging system the application has chosen. However, this pattern requires more complex APIs and places additional burden on library users to understand and configure logging dependencies.

Each approach represents a reasonable solution to a genuine problem, but none fully addresses the core tension: how do you provide valuable diagnostic capabilities without imposing choices on your users?

The fragmentation problem

There's another challenge that emerges when libraries each solve logging in their own way: fragmentation. Consider a typical Node.js application that might use Express for the web framework, Socket.IO for real-time communication, Axios for HTTP requests, Mongoose for database access, and several other specialized libraries.

Each library potentially has its own logging approach:

• Express uses DEBUG=express:*
• Socket.IO uses DEBUG=socket.io:*
• Mongoose uses mongoose.set('debug', true)
• Axios might use axios-logger or similar packages
• Redis clients have their own debug configurations
• Authentication libraries often include their own logging mechanisms

From an application developer's perspective, this creates a management challenge. They must learn and configure multiple different logging systems, each with its own syntax, capabilities, and quirks. Logs are scattered across different outputs with inconsistent formats, making it difficult to get a unified view of what's happening in their application.

The lack of integration also means that powerful features like structured logging, log correlation, and centralized log management become much harder to implement consistently across all the libraries in use.

LogTape's approach

LogTape attempts to address these challenges with what might be called a “library-first design.” The core principle is simple but potentially powerful: if logging isn't configured, nothing happens. No output, no errors, no side effects—just complete transparency.

This approach allows you to add comprehensive logging to your library without any impact on users who don't want it. When a user imports your library and runs their code, LogTape's logging calls are essentially no-ops until someone explicitly configures logging. Users who want insights into your library's behavior can opt in; those who don't are completely unaffected.

More importantly, when users do choose to configure logging, all LogTape-enabled libraries can be managed through a single, unified configuration system. This means one consistent API, one log format, and one destination for all library logs while still allowing fine-grained control over what gets logged from which libraries.

// In your library code - completely safe to include
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-awesome-lib", "database"]);

export function connectToDatabase(config) {
  logger.debug("Attempting database connection", { config });
  // ... your logic
  logger.info("Database connection established");
}

The dependency consideration

Modern JavaScript development involves careful consideration of dependencies. While popular logging libraries like winston and Pino are well-maintained and widely trusted, they do come with their own dependency trees. winston, for example, includes 17 dependencies, while Pino includes 1.

For library authors, this creates a consideration: every dependency you add becomes a dependency for your users, whether they want it or not. This isn't necessarily problematic (many excellent libraries have dependencies), but it does represent a choice you're making on behalf of your users.

LogTape takes a different approach with zero dependencies. This isn't just a philosophical choice—it has practical implications for your library's users. They won't see additional packages in their node_modules, won't need to worry about supply chain considerations for logging-related dependencies, and won't face potential version conflicts between your logging choice and theirs.

At just 5.3KB minified and gzipped, LogTape adds minimal weight to their bundles. The installation process becomes faster, the dependency tree stays cleaner, and security audits remain focused on the dependencies that directly serve your library's core functionality.

Breaking the compatibility chain

Here's a challenge that might be familiar: you want your library to support both ESM and CommonJS environments. Perhaps some of your users are working with legacy Node.js projects that rely on CommonJS, while others are using modern ESM setups or building for browsers.

The challenge becomes apparent when you have dependencies. While ESM modules can import CommonJS modules without issues, the reverse isn't true—CommonJS modules cannot require ESM-only packages (at least not until the experimental features in Node.js 22+ become stable). This creates an asymmetric compatibility constraint.

If your library depends on any ESM-only packages, your library effectively becomes ESM-only as well, since CommonJS environments won't be able to use it. This means that even one ESM-only dependency in your chain can prevent you from supporting CommonJS users.

LogTape supports both ESM and CommonJS completely, meaning it won't be the weak link that forces this limitation. Whether your users are working with legacy Node.js projects, cutting-edge ESM applications, or hybrid environments, LogTape adapts seamlessly to their setup.

More importantly, when LogTape provides native ESM support (rather than just being importable as CommonJS), it enables tree shaking in modern bundlers. Tree shaking allows bundlers to eliminate unused code during the build process, but it requires the static import/export structure that only ESM provides. While CommonJS modules can be imported into ESM projects, they're often treated as opaque blocks that can't be optimized, potentially including unused code in the final bundle.

For a logging library that aims to have minimal impact, this optimization capability can be meaningful, especially for applications where bundle size matters.

Universal runtime support

The JavaScript ecosystem spans an impressive range of runtime environments today. Your library might run in Node.js servers, Deno scripts, Bun applications, web browsers, or edge functions. LogTape works identically across all of these environments without requiring polyfills, compatibility layers, or runtime-specific code.

This universality means you can focus on your library's core functionality rather than worrying about whether your logging choice will work in every environment your users might encounter. Whether someone imports your library into a Cloudflare Worker, a Next.js application, or a Deno CLI tool, the logging behavior remains consistent and reliable.

Performance without compromise

One concern library authors often have about logging is performance impact. What if your users import your library into a high-performance application? What if they're running in a memory-constrained environment?

LogTape addresses this with remarkable efficiency when logging is disabled. The overhead of an unconfigured LogTape call is virtually zero—among the lowest of any logging solution available. This means you can add detailed logging throughout your library for development and debugging purposes without worrying about performance impact on users who don't enable it.

When logging is enabled, LogTape consistently outperforms other libraries, particularly for console output—often the most common logging destination during development.

Avoiding namespace collisions

Libraries sharing the same application can create logging chaos when they all output to the same namespace. LogTape's hierarchical category system elegantly solves this by encouraging libraries to use their own namespaces.

Your library might use categories like ["my-awesome-lib", "database"] or ["my-awesome-lib", "validation"], ensuring that your logs are clearly separated from other libraries and the main application. Users who configure LogTape can then control logging levels independently for different libraries and different components within those libraries.

Developer experience that just works

LogTape is built with TypeScript from the ground up, meaning your TypeScript-based library gets full type safety without additional dependencies or type packages. The API feels natural and modern, supporting both template literals and structured logging patterns that integrate well with contemporary JavaScript development practices.

// Template literal style - feels natural
logger.info`User ${userId} performed action ${action}`;

// Structured logging - great for monitoring
logger.info("User action completed", { userId, action, duration });

Practical integration

Actually using LogTape in your library is refreshingly straightforward. You simply import the logger, create appropriately namespaced categories, and log where it makes sense. No configuration, no setup, no complex initialization sequences.

import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-lib", "api"]);

export async function fetchUserData(userId) {
  logger.debug("Fetching user data", { userId });
  
  try {
    const response = await api.get(`/users/${userId}`);
    logger.info("User data retrieved successfully", { 
      userId, 
      status: response.status 
    });
    return response.data;
  } catch (error) {
    logger.error("Failed to fetch user data", { userId, error });
    throw error;
  }
}

For users who want to see these logs, configuration is equally simple:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: ["my-lib"], lowestLevel: "info", sinks: ["console"] }
  ]
});

Bridging the transition

If your potential users are already invested in other logging systems, LogTape provides adapters for popular libraries like winston and Pino. This allows LogTape-enabled libraries to integrate with existing logging infrastructure, routing their logs through whatever system applications are already using.

The existence of these adapters reveals an honest truth: LogTape isn't yet a widely-adopted standard in the JavaScript ecosystem. Most applications are still built around established logging libraries, and asking users to completely restructure their logging approach would be unrealistic. The adapters represent a practical compromise—they allow library authors to take advantage of LogTape's library-friendly design while respecting users' existing investments and preferences.

This approach reduces friction for adoption while still providing library authors with a modern, zero-dependency logging API. Perhaps over time, as more libraries adopt this pattern and more developers experience its benefits, the need for such adapters might diminish. But for now, they serve as a pragmatic bridge between LogTape's vision and the current reality of the ecosystem.

A choice worth considering

Ultimately, choosing LogTape for your library represents a particular philosophy about the relationship between libraries and applications. It's about providing capabilities while preserving choice, offering insights while avoiding imposition.

The traditional approaches—whether using debug packages, application-focused loggers, or custom solutions—each have their merits and have served the community well. LogTape simply offers another option: one designed specifically for the unique position libraries occupy in the JavaScript ecosystem.

For library authors, this approach might offer several practical benefits. Your library gets detailed logging for development, debugging, and user support, while your users retain complete autonomy over whether and how to use those capabilities.

The broader benefit might be a more cohesive logging experience across the JavaScript ecosystem—one where libraries can provide rich diagnostic information that integrates seamlessly with whatever logging strategy applications choose to employ.

In a world where every dependency decision has implications, LogTape offers an approach worth considering: a way to enhance your library's capabilities while respecting your users' preferences and existing choices.

Just shared my thoughts on #JavaScript library #logging on Hacker News. Explores the fragmentation problem and dependency dilemmas from a library author's perspective. Would love to hear feedback from the #winston/#Pino users.

https://news.ycombinator.com/item?id=44351881

---

Building a JavaScript library is a delicate balance. You want to provide useful functionality while being respectful of your users' choices and constraints. When it comes to logging—something many libraries need for debugging, monitoring, and user support—this balance becomes particularly challenging.

The JavaScript ecosystem has evolved various approaches to this challenge, each with its own trade-offs. LogTape offers a different path, one that's specifically designed with library authors in mind.

The current state of library logging

If you've built libraries before, you've probably encountered the logging dilemma. Your library would benefit from logging—perhaps to help users debug integration issues, trace internal state changes, or provide insights into performance bottlenecks. But how do you add this capability responsibly?

Currently, popular libraries handle this challenge in several ways:

The debug approach

Libraries like Express and Socket.IO use the lightweight debug package, which allows users to enable logging through environment variables (DEBUG=express:*). This works well but creates a separate logging system that doesn't integrate with users' existing logging infrastructure.

Custom logging systems

Libraries like Mongoose and Prisma have built their own logging mechanisms. Mongoose offers mongoose.set('debug', true) while Prisma uses its own logging configuration. These approaches work, but each library creates its own logging API that users must learn separately.

Application-focused libraries

winston, Pino, and Bunyan are powerful logging solutions, but they're primarily designed for applications rather than libraries. Using them in a library means imposing significant dependencies and potentially conflicting with users' existing logging choices.

No logging at all

Many library authors avoid the complexity entirely, leaving their libraries silent and making debugging more challenging for everyone involved.

Dependency injection

Some libraries adopt a more sophisticated approach by accepting a logger instance from the application through their configuration or constructor parameters. This maintains clean separation of concerns and allows libraries to use whatever logging system the application has chosen. However, this pattern requires more complex APIs and places additional burden on library users to understand and configure logging dependencies.

Each approach represents a reasonable solution to a genuine problem, but none fully addresses the core tension: how do you provide valuable diagnostic capabilities without imposing choices on your users?

The fragmentation problem

There's another challenge that emerges when libraries each solve logging in their own way: fragmentation. Consider a typical Node.js application that might use Express for the web framework, Socket.IO for real-time communication, Axios for HTTP requests, Mongoose for database access, and several other specialized libraries.

Each library potentially has its own logging approach:

• Express uses DEBUG=express:*
• Socket.IO uses DEBUG=socket.io:*
• Mongoose uses mongoose.set('debug', true)
• Axios might use axios-logger or similar packages
• Redis clients have their own debug configurations
• Authentication libraries often include their own logging mechanisms

From an application developer's perspective, this creates a management challenge. They must learn and configure multiple different logging systems, each with its own syntax, capabilities, and quirks. Logs are scattered across different outputs with inconsistent formats, making it difficult to get a unified view of what's happening in their application.

The lack of integration also means that powerful features like structured logging, log correlation, and centralized log management become much harder to implement consistently across all the libraries in use.

LogTape's approach

LogTape attempts to address these challenges with what might be called a “library-first design.” The core principle is simple but potentially powerful: if logging isn't configured, nothing happens. No output, no errors, no side effects—just complete transparency.

This approach allows you to add comprehensive logging to your library without any impact on users who don't want it. When a user imports your library and runs their code, LogTape's logging calls are essentially no-ops until someone explicitly configures logging. Users who want insights into your library's behavior can opt in; those who don't are completely unaffected.

More importantly, when users do choose to configure logging, all LogTape-enabled libraries can be managed through a single, unified configuration system. This means one consistent API, one log format, and one destination for all library logs while still allowing fine-grained control over what gets logged from which libraries.

// In your library code - completely safe to include
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-awesome-lib", "database"]);

export function connectToDatabase(config) {
  logger.debug("Attempting database connection", { config });
  // ... your logic
  logger.info("Database connection established");
}

The dependency consideration

Modern JavaScript development involves careful consideration of dependencies. While popular logging libraries like winston and Pino are well-maintained and widely trusted, they do come with their own dependency trees. winston, for example, includes 17 dependencies, while Pino includes 1.

For library authors, this creates a consideration: every dependency you add becomes a dependency for your users, whether they want it or not. This isn't necessarily problematic (many excellent libraries have dependencies), but it does represent a choice you're making on behalf of your users.

LogTape takes a different approach with zero dependencies. This isn't just a philosophical choice—it has practical implications for your library's users. They won't see additional packages in their node_modules, won't need to worry about supply chain considerations for logging-related dependencies, and won't face potential version conflicts between your logging choice and theirs.

At just 5.3KB minified and gzipped, LogTape adds minimal weight to their bundles. The installation process becomes faster, the dependency tree stays cleaner, and security audits remain focused on the dependencies that directly serve your library's core functionality.

Breaking the compatibility chain

Here's a challenge that might be familiar: you want your library to support both ESM and CommonJS environments. Perhaps some of your users are working with legacy Node.js projects that rely on CommonJS, while others are using modern ESM setups or building for browsers.

The challenge becomes apparent when you have dependencies. While ESM modules can import CommonJS modules without issues, the reverse isn't true—CommonJS modules cannot require ESM-only packages (at least not until the experimental features in Node.js 22+ become stable). This creates an asymmetric compatibility constraint.

If your library depends on any ESM-only packages, your library effectively becomes ESM-only as well, since CommonJS environments won't be able to use it. This means that even one ESM-only dependency in your chain can prevent you from supporting CommonJS users.

LogTape supports both ESM and CommonJS completely, meaning it won't be the weak link that forces this limitation. Whether your users are working with legacy Node.js projects, cutting-edge ESM applications, or hybrid environments, LogTape adapts seamlessly to their setup.

More importantly, when LogTape provides native ESM support (rather than just being importable as CommonJS), it enables tree shaking in modern bundlers. Tree shaking allows bundlers to eliminate unused code during the build process, but it requires the static import/export structure that only ESM provides. While CommonJS modules can be imported into ESM projects, they're often treated as opaque blocks that can't be optimized, potentially including unused code in the final bundle.

For a logging library that aims to have minimal impact, this optimization capability can be meaningful, especially for applications where bundle size matters.

Universal runtime support

The JavaScript ecosystem spans an impressive range of runtime environments today. Your library might run in Node.js servers, Deno scripts, Bun applications, web browsers, or edge functions. LogTape works identically across all of these environments without requiring polyfills, compatibility layers, or runtime-specific code.

This universality means you can focus on your library's core functionality rather than worrying about whether your logging choice will work in every environment your users might encounter. Whether someone imports your library into a Cloudflare Worker, a Next.js application, or a Deno CLI tool, the logging behavior remains consistent and reliable.

Performance without compromise

One concern library authors often have about logging is performance impact. What if your users import your library into a high-performance application? What if they're running in a memory-constrained environment?

LogTape addresses this with remarkable efficiency when logging is disabled. The overhead of an unconfigured LogTape call is virtually zero—among the lowest of any logging solution available. This means you can add detailed logging throughout your library for development and debugging purposes without worrying about performance impact on users who don't enable it.

When logging is enabled, LogTape consistently outperforms other libraries, particularly for console output—often the most common logging destination during development.

Avoiding namespace collisions

Libraries sharing the same application can create logging chaos when they all output to the same namespace. LogTape's hierarchical category system elegantly solves this by encouraging libraries to use their own namespaces.

Your library might use categories like ["my-awesome-lib", "database"] or ["my-awesome-lib", "validation"], ensuring that your logs are clearly separated from other libraries and the main application. Users who configure LogTape can then control logging levels independently for different libraries and different components within those libraries.

Developer experience that just works

LogTape is built with TypeScript from the ground up, meaning your TypeScript-based library gets full type safety without additional dependencies or type packages. The API feels natural and modern, supporting both template literals and structured logging patterns that integrate well with contemporary JavaScript development practices.

// Template literal style - feels natural
logger.info`User ${userId} performed action ${action}`;

// Structured logging - great for monitoring
logger.info("User action completed", { userId, action, duration });

Practical integration

Actually using LogTape in your library is refreshingly straightforward. You simply import the logger, create appropriately namespaced categories, and log where it makes sense. No configuration, no setup, no complex initialization sequences.

import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-lib", "api"]);

export async function fetchUserData(userId) {
  logger.debug("Fetching user data", { userId });
  
  try {
    const response = await api.get(`/users/${userId}`);
    logger.info("User data retrieved successfully", { 
      userId, 
      status: response.status 
    });
    return response.data;
  } catch (error) {
    logger.error("Failed to fetch user data", { userId, error });
    throw error;
  }
}

For users who want to see these logs, configuration is equally simple:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: ["my-lib"], lowestLevel: "info", sinks: ["console"] }
  ]
});

Bridging the transition

If your potential users are already invested in other logging systems, LogTape provides adapters for popular libraries like winston and Pino. This allows LogTape-enabled libraries to integrate with existing logging infrastructure, routing their logs through whatever system applications are already using.

The existence of these adapters reveals an honest truth: LogTape isn't yet a widely-adopted standard in the JavaScript ecosystem. Most applications are still built around established logging libraries, and asking users to completely restructure their logging approach would be unrealistic. The adapters represent a practical compromise—they allow library authors to take advantage of LogTape's library-friendly design while respecting users' existing investments and preferences.

This approach reduces friction for adoption while still providing library authors with a modern, zero-dependency logging API. Perhaps over time, as more libraries adopt this pattern and more developers experience its benefits, the need for such adapters might diminish. But for now, they serve as a pragmatic bridge between LogTape's vision and the current reality of the ecosystem.

A choice worth considering

Ultimately, choosing LogTape for your library represents a particular philosophy about the relationship between libraries and applications. It's about providing capabilities while preserving choice, offering insights while avoiding imposition.

The traditional approaches—whether using debug packages, application-focused loggers, or custom solutions—each have their merits and have served the community well. LogTape simply offers another option: one designed specifically for the unique position libraries occupy in the JavaScript ecosystem.

For library authors, this approach might offer several practical benefits. Your library gets detailed logging for development, debugging, and user support, while your users retain complete autonomy over whether and how to use those capabilities.

The broader benefit might be a more cohesive logging experience across the JavaScript ecosystem—one where libraries can provide rich diagnostic information that integrates seamlessly with whatever logging strategy applications choose to employ.

In a world where every dependency decision has implications, LogTape offers an approach worth considering: a way to enhance your library's capabilities while respecting your users' preferences and existing choices.

Just shared my thoughts on #JavaScript library #logging on Hacker News. Explores the fragmentation problem and dependency dilemmas from a library author's perspective. Would love to hear feedback from the #winston/#Pino users.

https://news.ycombinator.com/item?id=44351881

---

Building a JavaScript library is a delicate balance. You want to provide useful functionality while being respectful of your users' choices and constraints. When it comes to logging—something many libraries need for debugging, monitoring, and user support—this balance becomes particularly challenging.

The JavaScript ecosystem has evolved various approaches to this challenge, each with its own trade-offs. LogTape offers a different path, one that's specifically designed with library authors in mind.

The current state of library logging

If you've built libraries before, you've probably encountered the logging dilemma. Your library would benefit from logging—perhaps to help users debug integration issues, trace internal state changes, or provide insights into performance bottlenecks. But how do you add this capability responsibly?

Currently, popular libraries handle this challenge in several ways:

The debug approach

Libraries like Express and Socket.IO use the lightweight debug package, which allows users to enable logging through environment variables (DEBUG=express:*). This works well but creates a separate logging system that doesn't integrate with users' existing logging infrastructure.

Custom logging systems

Libraries like Mongoose and Prisma have built their own logging mechanisms. Mongoose offers mongoose.set('debug', true) while Prisma uses its own logging configuration. These approaches work, but each library creates its own logging API that users must learn separately.

Application-focused libraries

winston, Pino, and Bunyan are powerful logging solutions, but they're primarily designed for applications rather than libraries. Using them in a library means imposing significant dependencies and potentially conflicting with users' existing logging choices.

No logging at all

Many library authors avoid the complexity entirely, leaving their libraries silent and making debugging more challenging for everyone involved.

Dependency injection

Some libraries adopt a more sophisticated approach by accepting a logger instance from the application through their configuration or constructor parameters. This maintains clean separation of concerns and allows libraries to use whatever logging system the application has chosen. However, this pattern requires more complex APIs and places additional burden on library users to understand and configure logging dependencies.

Each approach represents a reasonable solution to a genuine problem, but none fully addresses the core tension: how do you provide valuable diagnostic capabilities without imposing choices on your users?

The fragmentation problem

There's another challenge that emerges when libraries each solve logging in their own way: fragmentation. Consider a typical Node.js application that might use Express for the web framework, Socket.IO for real-time communication, Axios for HTTP requests, Mongoose for database access, and several other specialized libraries.

Each library potentially has its own logging approach:

• Express uses DEBUG=express:*
• Socket.IO uses DEBUG=socket.io:*
• Mongoose uses mongoose.set('debug', true)
• Axios might use axios-logger or similar packages
• Redis clients have their own debug configurations
• Authentication libraries often include their own logging mechanisms

From an application developer's perspective, this creates a management challenge. They must learn and configure multiple different logging systems, each with its own syntax, capabilities, and quirks. Logs are scattered across different outputs with inconsistent formats, making it difficult to get a unified view of what's happening in their application.

The lack of integration also means that powerful features like structured logging, log correlation, and centralized log management become much harder to implement consistently across all the libraries in use.

LogTape's approach

LogTape attempts to address these challenges with what might be called a “library-first design.” The core principle is simple but potentially powerful: if logging isn't configured, nothing happens. No output, no errors, no side effects—just complete transparency.

This approach allows you to add comprehensive logging to your library without any impact on users who don't want it. When a user imports your library and runs their code, LogTape's logging calls are essentially no-ops until someone explicitly configures logging. Users who want insights into your library's behavior can opt in; those who don't are completely unaffected.

More importantly, when users do choose to configure logging, all LogTape-enabled libraries can be managed through a single, unified configuration system. This means one consistent API, one log format, and one destination for all library logs while still allowing fine-grained control over what gets logged from which libraries.

// In your library code - completely safe to include
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-awesome-lib", "database"]);

export function connectToDatabase(config) {
  logger.debug("Attempting database connection", { config });
  // ... your logic
  logger.info("Database connection established");
}

The dependency consideration

Modern JavaScript development involves careful consideration of dependencies. While popular logging libraries like winston and Pino are well-maintained and widely trusted, they do come with their own dependency trees. winston, for example, includes 17 dependencies, while Pino includes 1.

For library authors, this creates a consideration: every dependency you add becomes a dependency for your users, whether they want it or not. This isn't necessarily problematic (many excellent libraries have dependencies), but it does represent a choice you're making on behalf of your users.

LogTape takes a different approach with zero dependencies. This isn't just a philosophical choice—it has practical implications for your library's users. They won't see additional packages in their node_modules, won't need to worry about supply chain considerations for logging-related dependencies, and won't face potential version conflicts between your logging choice and theirs.

At just 5.3KB minified and gzipped, LogTape adds minimal weight to their bundles. The installation process becomes faster, the dependency tree stays cleaner, and security audits remain focused on the dependencies that directly serve your library's core functionality.

Breaking the compatibility chain

Here's a challenge that might be familiar: you want your library to support both ESM and CommonJS environments. Perhaps some of your users are working with legacy Node.js projects that rely on CommonJS, while others are using modern ESM setups or building for browsers.

The challenge becomes apparent when you have dependencies. While ESM modules can import CommonJS modules without issues, the reverse isn't true—CommonJS modules cannot require ESM-only packages (at least not until the experimental features in Node.js 22+ become stable). This creates an asymmetric compatibility constraint.

If your library depends on any ESM-only packages, your library effectively becomes ESM-only as well, since CommonJS environments won't be able to use it. This means that even one ESM-only dependency in your chain can prevent you from supporting CommonJS users.

LogTape supports both ESM and CommonJS completely, meaning it won't be the weak link that forces this limitation. Whether your users are working with legacy Node.js projects, cutting-edge ESM applications, or hybrid environments, LogTape adapts seamlessly to their setup.

More importantly, when LogTape provides native ESM support (rather than just being importable as CommonJS), it enables tree shaking in modern bundlers. Tree shaking allows bundlers to eliminate unused code during the build process, but it requires the static import/export structure that only ESM provides. While CommonJS modules can be imported into ESM projects, they're often treated as opaque blocks that can't be optimized, potentially including unused code in the final bundle.

For a logging library that aims to have minimal impact, this optimization capability can be meaningful, especially for applications where bundle size matters.

Universal runtime support

The JavaScript ecosystem spans an impressive range of runtime environments today. Your library might run in Node.js servers, Deno scripts, Bun applications, web browsers, or edge functions. LogTape works identically across all of these environments without requiring polyfills, compatibility layers, or runtime-specific code.

This universality means you can focus on your library's core functionality rather than worrying about whether your logging choice will work in every environment your users might encounter. Whether someone imports your library into a Cloudflare Worker, a Next.js application, or a Deno CLI tool, the logging behavior remains consistent and reliable.

Performance without compromise

One concern library authors often have about logging is performance impact. What if your users import your library into a high-performance application? What if they're running in a memory-constrained environment?

LogTape addresses this with remarkable efficiency when logging is disabled. The overhead of an unconfigured LogTape call is virtually zero—among the lowest of any logging solution available. This means you can add detailed logging throughout your library for development and debugging purposes without worrying about performance impact on users who don't enable it.

When logging is enabled, LogTape consistently outperforms other libraries, particularly for console output—often the most common logging destination during development.

Avoiding namespace collisions

Libraries sharing the same application can create logging chaos when they all output to the same namespace. LogTape's hierarchical category system elegantly solves this by encouraging libraries to use their own namespaces.

Your library might use categories like ["my-awesome-lib", "database"] or ["my-awesome-lib", "validation"], ensuring that your logs are clearly separated from other libraries and the main application. Users who configure LogTape can then control logging levels independently for different libraries and different components within those libraries.

Developer experience that just works

LogTape is built with TypeScript from the ground up, meaning your TypeScript-based library gets full type safety without additional dependencies or type packages. The API feels natural and modern, supporting both template literals and structured logging patterns that integrate well with contemporary JavaScript development practices.

// Template literal style - feels natural
logger.info`User ${userId} performed action ${action}`;

// Structured logging - great for monitoring
logger.info("User action completed", { userId, action, duration });

Practical integration

Actually using LogTape in your library is refreshingly straightforward. You simply import the logger, create appropriately namespaced categories, and log where it makes sense. No configuration, no setup, no complex initialization sequences.

import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-lib", "api"]);

export async function fetchUserData(userId) {
  logger.debug("Fetching user data", { userId });
  
  try {
    const response = await api.get(`/users/${userId}`);
    logger.info("User data retrieved successfully", { 
      userId, 
      status: response.status 
    });
    return response.data;
  } catch (error) {
    logger.error("Failed to fetch user data", { userId, error });
    throw error;
  }
}

For users who want to see these logs, configuration is equally simple:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: ["my-lib"], lowestLevel: "info", sinks: ["console"] }
  ]
});

Bridging the transition

If your potential users are already invested in other logging systems, LogTape provides adapters for popular libraries like winston and Pino. This allows LogTape-enabled libraries to integrate with existing logging infrastructure, routing their logs through whatever system applications are already using.

The existence of these adapters reveals an honest truth: LogTape isn't yet a widely-adopted standard in the JavaScript ecosystem. Most applications are still built around established logging libraries, and asking users to completely restructure their logging approach would be unrealistic. The adapters represent a practical compromise—they allow library authors to take advantage of LogTape's library-friendly design while respecting users' existing investments and preferences.

This approach reduces friction for adoption while still providing library authors with a modern, zero-dependency logging API. Perhaps over time, as more libraries adopt this pattern and more developers experience its benefits, the need for such adapters might diminish. But for now, they serve as a pragmatic bridge between LogTape's vision and the current reality of the ecosystem.

A choice worth considering

Ultimately, choosing LogTape for your library represents a particular philosophy about the relationship between libraries and applications. It's about providing capabilities while preserving choice, offering insights while avoiding imposition.

The traditional approaches—whether using debug packages, application-focused loggers, or custom solutions—each have their merits and have served the community well. LogTape simply offers another option: one designed specifically for the unique position libraries occupy in the JavaScript ecosystem.

For library authors, this approach might offer several practical benefits. Your library gets detailed logging for development, debugging, and user support, while your users retain complete autonomy over whether and how to use those capabilities.

The broader benefit might be a more cohesive logging experience across the JavaScript ecosystem—one where libraries can provide rich diagnostic information that integrates seamlessly with whatever logging strategy applications choose to employ.

In a world where every dependency decision has implications, LogTape offers an approach worth considering: a way to enhance your library's capabilities while respecting your users' preferences and existing choices.

---

Building a JavaScript library is a delicate balance. You want to provide useful functionality while being respectful of your users' choices and constraints. When it comes to logging—something many libraries need for debugging, monitoring, and user support—this balance becomes particularly challenging.

The JavaScript ecosystem has evolved various approaches to this challenge, each with its own trade-offs. LogTape offers a different path, one that's specifically designed with library authors in mind.

The current state of library logging

If you've built libraries before, you've probably encountered the logging dilemma. Your library would benefit from logging—perhaps to help users debug integration issues, trace internal state changes, or provide insights into performance bottlenecks. But how do you add this capability responsibly?

Currently, popular libraries handle this challenge in several ways:

The debug approach

Libraries like Express and Socket.IO use the lightweight debug package, which allows users to enable logging through environment variables (DEBUG=express:*). This works well but creates a separate logging system that doesn't integrate with users' existing logging infrastructure.

Custom logging systems

Libraries like Mongoose and Prisma have built their own logging mechanisms. Mongoose offers mongoose.set('debug', true) while Prisma uses its own logging configuration. These approaches work, but each library creates its own logging API that users must learn separately.

Application-focused libraries

winston, Pino, and Bunyan are powerful logging solutions, but they're primarily designed for applications rather than libraries. Using them in a library means imposing significant dependencies and potentially conflicting with users' existing logging choices.

No logging at all

Many library authors avoid the complexity entirely, leaving their libraries silent and making debugging more challenging for everyone involved.

Dependency injection

Some libraries adopt a more sophisticated approach by accepting a logger instance from the application through their configuration or constructor parameters. This maintains clean separation of concerns and allows libraries to use whatever logging system the application has chosen. However, this pattern requires more complex APIs and places additional burden on library users to understand and configure logging dependencies.

Each approach represents a reasonable solution to a genuine problem, but none fully addresses the core tension: how do you provide valuable diagnostic capabilities without imposing choices on your users?

The fragmentation problem

There's another challenge that emerges when libraries each solve logging in their own way: fragmentation. Consider a typical Node.js application that might use Express for the web framework, Socket.IO for real-time communication, Axios for HTTP requests, Mongoose for database access, and several other specialized libraries.

Each library potentially has its own logging approach:

• Express uses DEBUG=express:*
• Socket.IO uses DEBUG=socket.io:*
• Mongoose uses mongoose.set('debug', true)
• Axios might use axios-logger or similar packages
• Redis clients have their own debug configurations
• Authentication libraries often include their own logging mechanisms

From an application developer's perspective, this creates a management challenge. They must learn and configure multiple different logging systems, each with its own syntax, capabilities, and quirks. Logs are scattered across different outputs with inconsistent formats, making it difficult to get a unified view of what's happening in their application.

The lack of integration also means that powerful features like structured logging, log correlation, and centralized log management become much harder to implement consistently across all the libraries in use.

LogTape's approach

LogTape attempts to address these challenges with what might be called a “library-first design.” The core principle is simple but potentially powerful: if logging isn't configured, nothing happens. No output, no errors, no side effects—just complete transparency.

This approach allows you to add comprehensive logging to your library without any impact on users who don't want it. When a user imports your library and runs their code, LogTape's logging calls are essentially no-ops until someone explicitly configures logging. Users who want insights into your library's behavior can opt in; those who don't are completely unaffected.

More importantly, when users do choose to configure logging, all LogTape-enabled libraries can be managed through a single, unified configuration system. This means one consistent API, one log format, and one destination for all library logs while still allowing fine-grained control over what gets logged from which libraries.

// In your library code - completely safe to include
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-awesome-lib", "database"]);

export function connectToDatabase(config) {
  logger.debug("Attempting database connection", { config });
  // ... your logic
  logger.info("Database connection established");
}

The dependency consideration

Modern JavaScript development involves careful consideration of dependencies. While popular logging libraries like winston and Pino are well-maintained and widely trusted, they do come with their own dependency trees. winston, for example, includes 17 dependencies, while Pino includes 1.

For library authors, this creates a consideration: every dependency you add becomes a dependency for your users, whether they want it or not. This isn't necessarily problematic (many excellent libraries have dependencies), but it does represent a choice you're making on behalf of your users.

LogTape takes a different approach with zero dependencies. This isn't just a philosophical choice—it has practical implications for your library's users. They won't see additional packages in their node_modules, won't need to worry about supply chain considerations for logging-related dependencies, and won't face potential version conflicts between your logging choice and theirs.

At just 5.3KB minified and gzipped, LogTape adds minimal weight to their bundles. The installation process becomes faster, the dependency tree stays cleaner, and security audits remain focused on the dependencies that directly serve your library's core functionality.

Breaking the compatibility chain

Here's a challenge that might be familiar: you want your library to support both ESM and CommonJS environments. Perhaps some of your users are working with legacy Node.js projects that rely on CommonJS, while others are using modern ESM setups or building for browsers.

The challenge becomes apparent when you have dependencies. While ESM modules can import CommonJS modules without issues, the reverse isn't true—CommonJS modules cannot require ESM-only packages (at least not until the experimental features in Node.js 22+ become stable). This creates an asymmetric compatibility constraint.

If your library depends on any ESM-only packages, your library effectively becomes ESM-only as well, since CommonJS environments won't be able to use it. This means that even one ESM-only dependency in your chain can prevent you from supporting CommonJS users.

LogTape supports both ESM and CommonJS completely, meaning it won't be the weak link that forces this limitation. Whether your users are working with legacy Node.js projects, cutting-edge ESM applications, or hybrid environments, LogTape adapts seamlessly to their setup.

More importantly, when LogTape provides native ESM support (rather than just being importable as CommonJS), it enables tree shaking in modern bundlers. Tree shaking allows bundlers to eliminate unused code during the build process, but it requires the static import/export structure that only ESM provides. While CommonJS modules can be imported into ESM projects, they're often treated as opaque blocks that can't be optimized, potentially including unused code in the final bundle.

For a logging library that aims to have minimal impact, this optimization capability can be meaningful, especially for applications where bundle size matters.

Universal runtime support

The JavaScript ecosystem spans an impressive range of runtime environments today. Your library might run in Node.js servers, Deno scripts, Bun applications, web browsers, or edge functions. LogTape works identically across all of these environments without requiring polyfills, compatibility layers, or runtime-specific code.

This universality means you can focus on your library's core functionality rather than worrying about whether your logging choice will work in every environment your users might encounter. Whether someone imports your library into a Cloudflare Worker, a Next.js application, or a Deno CLI tool, the logging behavior remains consistent and reliable.

Performance without compromise

One concern library authors often have about logging is performance impact. What if your users import your library into a high-performance application? What if they're running in a memory-constrained environment?

LogTape addresses this with remarkable efficiency when logging is disabled. The overhead of an unconfigured LogTape call is virtually zero—among the lowest of any logging solution available. This means you can add detailed logging throughout your library for development and debugging purposes without worrying about performance impact on users who don't enable it.

When logging is enabled, LogTape consistently outperforms other libraries, particularly for console output—often the most common logging destination during development.

Avoiding namespace collisions

Libraries sharing the same application can create logging chaos when they all output to the same namespace. LogTape's hierarchical category system elegantly solves this by encouraging libraries to use their own namespaces.

Your library might use categories like ["my-awesome-lib", "database"] or ["my-awesome-lib", "validation"], ensuring that your logs are clearly separated from other libraries and the main application. Users who configure LogTape can then control logging levels independently for different libraries and different components within those libraries.

Developer experience that just works

LogTape is built with TypeScript from the ground up, meaning your TypeScript-based library gets full type safety without additional dependencies or type packages. The API feels natural and modern, supporting both template literals and structured logging patterns that integrate well with contemporary JavaScript development practices.

// Template literal style - feels natural
logger.info`User ${userId} performed action ${action}`;

// Structured logging - great for monitoring
logger.info("User action completed", { userId, action, duration });

Practical integration

Actually using LogTape in your library is refreshingly straightforward. You simply import the logger, create appropriately namespaced categories, and log where it makes sense. No configuration, no setup, no complex initialization sequences.

import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-lib", "api"]);

export async function fetchUserData(userId) {
  logger.debug("Fetching user data", { userId });
  
  try {
    const response = await api.get(`/users/${userId}`);
    logger.info("User data retrieved successfully", { 
      userId, 
      status: response.status 
    });
    return response.data;
  } catch (error) {
    logger.error("Failed to fetch user data", { userId, error });
    throw error;
  }
}

For users who want to see these logs, configuration is equally simple:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: ["my-lib"], lowestLevel: "info", sinks: ["console"] }
  ]
});

Bridging the transition

If your potential users are already invested in other logging systems, LogTape provides adapters for popular libraries like winston and Pino. This allows LogTape-enabled libraries to integrate with existing logging infrastructure, routing their logs through whatever system applications are already using.

The existence of these adapters reveals an honest truth: LogTape isn't yet a widely-adopted standard in the JavaScript ecosystem. Most applications are still built around established logging libraries, and asking users to completely restructure their logging approach would be unrealistic. The adapters represent a practical compromise—they allow library authors to take advantage of LogTape's library-friendly design while respecting users' existing investments and preferences.

This approach reduces friction for adoption while still providing library authors with a modern, zero-dependency logging API. Perhaps over time, as more libraries adopt this pattern and more developers experience its benefits, the need for such adapters might diminish. But for now, they serve as a pragmatic bridge between LogTape's vision and the current reality of the ecosystem.

A choice worth considering

Ultimately, choosing LogTape for your library represents a particular philosophy about the relationship between libraries and applications. It's about providing capabilities while preserving choice, offering insights while avoiding imposition.

The traditional approaches—whether using debug packages, application-focused loggers, or custom solutions—each have their merits and have served the community well. LogTape simply offers another option: one designed specifically for the unique position libraries occupy in the JavaScript ecosystem.

For library authors, this approach might offer several practical benefits. Your library gets detailed logging for development, debugging, and user support, while your users retain complete autonomy over whether and how to use those capabilities.

The broader benefit might be a more cohesive logging experience across the JavaScript ecosystem—one where libraries can provide rich diagnostic information that integrates seamlessly with whatever logging strategy applications choose to employ.

In a world where every dependency decision has implications, LogTape offers an approach worth considering: a way to enhance your library's capabilities while respecting your users' preferences and existing choices.

---

Building a JavaScript library is a delicate balance. You want to provide useful functionality while being respectful of your users' choices and constraints. When it comes to logging—something many libraries need for debugging, monitoring, and user support—this balance becomes particularly challenging.

The JavaScript ecosystem has evolved various approaches to this challenge, each with its own trade-offs. LogTape offers a different path, one that's specifically designed with library authors in mind.

The current state of library logging

If you've built libraries before, you've probably encountered the logging dilemma. Your library would benefit from logging—perhaps to help users debug integration issues, trace internal state changes, or provide insights into performance bottlenecks. But how do you add this capability responsibly?

Currently, popular libraries handle this challenge in several ways:

The debug approach

Libraries like Express and Socket.IO use the lightweight debug package, which allows users to enable logging through environment variables (DEBUG=express:*). This works well but creates a separate logging system that doesn't integrate with users' existing logging infrastructure.

Custom logging systems

Libraries like Mongoose and Prisma have built their own logging mechanisms. Mongoose offers mongoose.set('debug', true) while Prisma uses its own logging configuration. These approaches work, but each library creates its own logging API that users must learn separately.

Application-focused libraries

winston, Pino, and Bunyan are powerful logging solutions, but they're primarily designed for applications rather than libraries. Using them in a library means imposing significant dependencies and potentially conflicting with users' existing logging choices.

No logging at all

Many library authors avoid the complexity entirely, leaving their libraries silent and making debugging more challenging for everyone involved.

Dependency injection

Some libraries adopt a more sophisticated approach by accepting a logger instance from the application through their configuration or constructor parameters. This maintains clean separation of concerns and allows libraries to use whatever logging system the application has chosen. However, this pattern requires more complex APIs and places additional burden on library users to understand and configure logging dependencies.

Each approach represents a reasonable solution to a genuine problem, but none fully addresses the core tension: how do you provide valuable diagnostic capabilities without imposing choices on your users?

The fragmentation problem

There's another challenge that emerges when libraries each solve logging in their own way: fragmentation. Consider a typical Node.js application that might use Express for the web framework, Socket.IO for real-time communication, Axios for HTTP requests, Mongoose for database access, and several other specialized libraries.

Each library potentially has its own logging approach:

• Express uses DEBUG=express:*
• Socket.IO uses DEBUG=socket.io:*
• Mongoose uses mongoose.set('debug', true)
• Axios might use axios-logger or similar packages
• Redis clients have their own debug configurations
• Authentication libraries often include their own logging mechanisms

From an application developer's perspective, this creates a management challenge. They must learn and configure multiple different logging systems, each with its own syntax, capabilities, and quirks. Logs are scattered across different outputs with inconsistent formats, making it difficult to get a unified view of what's happening in their application.

The lack of integration also means that powerful features like structured logging, log correlation, and centralized log management become much harder to implement consistently across all the libraries in use.

LogTape's approach

LogTape attempts to address these challenges with what might be called a “library-first design.” The core principle is simple but potentially powerful: if logging isn't configured, nothing happens. No output, no errors, no side effects—just complete transparency.

This approach allows you to add comprehensive logging to your library without any impact on users who don't want it. When a user imports your library and runs their code, LogTape's logging calls are essentially no-ops until someone explicitly configures logging. Users who want insights into your library's behavior can opt in; those who don't are completely unaffected.

More importantly, when users do choose to configure logging, all LogTape-enabled libraries can be managed through a single, unified configuration system. This means one consistent API, one log format, and one destination for all library logs while still allowing fine-grained control over what gets logged from which libraries.

// In your library code - completely safe to include
import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-awesome-lib", "database"]);

export function connectToDatabase(config) {
  logger.debug("Attempting database connection", { config });
  // ... your logic
  logger.info("Database connection established");
}

The dependency consideration

Modern JavaScript development involves careful consideration of dependencies. While popular logging libraries like winston and Pino are well-maintained and widely trusted, they do come with their own dependency trees. winston, for example, includes 17 dependencies, while Pino includes 1.

For library authors, this creates a consideration: every dependency you add becomes a dependency for your users, whether they want it or not. This isn't necessarily problematic (many excellent libraries have dependencies), but it does represent a choice you're making on behalf of your users.

LogTape takes a different approach with zero dependencies. This isn't just a philosophical choice—it has practical implications for your library's users. They won't see additional packages in their node_modules, won't need to worry about supply chain considerations for logging-related dependencies, and won't face potential version conflicts between your logging choice and theirs.

At just 5.3KB minified and gzipped, LogTape adds minimal weight to their bundles. The installation process becomes faster, the dependency tree stays cleaner, and security audits remain focused on the dependencies that directly serve your library's core functionality.

Breaking the compatibility chain

Here's a challenge that might be familiar: you want your library to support both ESM and CommonJS environments. Perhaps some of your users are working with legacy Node.js projects that rely on CommonJS, while others are using modern ESM setups or building for browsers.

The challenge becomes apparent when you have dependencies. While ESM modules can import CommonJS modules without issues, the reverse isn't true—CommonJS modules cannot require ESM-only packages (at least not until the experimental features in Node.js 22+ become stable). This creates an asymmetric compatibility constraint.

If your library depends on any ESM-only packages, your library effectively becomes ESM-only as well, since CommonJS environments won't be able to use it. This means that even one ESM-only dependency in your chain can prevent you from supporting CommonJS users.

LogTape supports both ESM and CommonJS completely, meaning it won't be the weak link that forces this limitation. Whether your users are working with legacy Node.js projects, cutting-edge ESM applications, or hybrid environments, LogTape adapts seamlessly to their setup.

More importantly, when LogTape provides native ESM support (rather than just being importable as CommonJS), it enables tree shaking in modern bundlers. Tree shaking allows bundlers to eliminate unused code during the build process, but it requires the static import/export structure that only ESM provides. While CommonJS modules can be imported into ESM projects, they're often treated as opaque blocks that can't be optimized, potentially including unused code in the final bundle.

For a logging library that aims to have minimal impact, this optimization capability can be meaningful, especially for applications where bundle size matters.

Universal runtime support

The JavaScript ecosystem spans an impressive range of runtime environments today. Your library might run in Node.js servers, Deno scripts, Bun applications, web browsers, or edge functions. LogTape works identically across all of these environments without requiring polyfills, compatibility layers, or runtime-specific code.

This universality means you can focus on your library's core functionality rather than worrying about whether your logging choice will work in every environment your users might encounter. Whether someone imports your library into a Cloudflare Worker, a Next.js application, or a Deno CLI tool, the logging behavior remains consistent and reliable.

Performance without compromise

One concern library authors often have about logging is performance impact. What if your users import your library into a high-performance application? What if they're running in a memory-constrained environment?

LogTape addresses this with remarkable efficiency when logging is disabled. The overhead of an unconfigured LogTape call is virtually zero—among the lowest of any logging solution available. This means you can add detailed logging throughout your library for development and debugging purposes without worrying about performance impact on users who don't enable it.

When logging is enabled, LogTape consistently outperforms other libraries, particularly for console output—often the most common logging destination during development.

Avoiding namespace collisions

Libraries sharing the same application can create logging chaos when they all output to the same namespace. LogTape's hierarchical category system elegantly solves this by encouraging libraries to use their own namespaces.

Your library might use categories like ["my-awesome-lib", "database"] or ["my-awesome-lib", "validation"], ensuring that your logs are clearly separated from other libraries and the main application. Users who configure LogTape can then control logging levels independently for different libraries and different components within those libraries.

Developer experience that just works

LogTape is built with TypeScript from the ground up, meaning your TypeScript-based library gets full type safety without additional dependencies or type packages. The API feels natural and modern, supporting both template literals and structured logging patterns that integrate well with contemporary JavaScript development practices.

// Template literal style - feels natural
logger.info`User ${userId} performed action ${action}`;

// Structured logging - great for monitoring
logger.info("User action completed", { userId, action, duration });

Practical integration

Actually using LogTape in your library is refreshingly straightforward. You simply import the logger, create appropriately namespaced categories, and log where it makes sense. No configuration, no setup, no complex initialization sequences.

import { getLogger } from "@logtape/logtape";

const logger = getLogger(["my-lib", "api"]);

export async function fetchUserData(userId) {
  logger.debug("Fetching user data", { userId });
  
  try {
    const response = await api.get(`/users/${userId}`);
    logger.info("User data retrieved successfully", { 
      userId, 
      status: response.status 
    });
    return response.data;
  } catch (error) {
    logger.error("Failed to fetch user data", { userId, error });
    throw error;
  }
}

For users who want to see these logs, configuration is equally simple:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: ["my-lib"], lowestLevel: "info", sinks: ["console"] }
  ]
});

Bridging the transition

If your potential users are already invested in other logging systems, LogTape provides adapters for popular libraries like winston and Pino. This allows LogTape-enabled libraries to integrate with existing logging infrastructure, routing their logs through whatever system applications are already using.

The existence of these adapters reveals an honest truth: LogTape isn't yet a widely-adopted standard in the JavaScript ecosystem. Most applications are still built around established logging libraries, and asking users to completely restructure their logging approach would be unrealistic. The adapters represent a practical compromise—they allow library authors to take advantage of LogTape's library-friendly design while respecting users' existing investments and preferences.

This approach reduces friction for adoption while still providing library authors with a modern, zero-dependency logging API. Perhaps over time, as more libraries adopt this pattern and more developers experience its benefits, the need for such adapters might diminish. But for now, they serve as a pragmatic bridge between LogTape's vision and the current reality of the ecosystem.

A choice worth considering

Ultimately, choosing LogTape for your library represents a particular philosophy about the relationship between libraries and applications. It's about providing capabilities while preserving choice, offering insights while avoiding imposition.

The traditional approaches—whether using debug packages, application-focused loggers, or custom solutions—each have their merits and have served the community well. LogTape simply offers another option: one designed specifically for the unique position libraries occupy in the JavaScript ecosystem.

For library authors, this approach might offer several practical benefits. Your library gets detailed logging for development, debugging, and user support, while your users retain complete autonomy over whether and how to use those capabilities.

The broader benefit might be a more cohesive logging experience across the JavaScript ecosystem—one where libraries can provide rich diagnostic information that integrates seamlessly with whatever logging strategy applications choose to employ.

In a world where every dependency decision has implications, LogTape offers an approach worth considering: a way to enhance your library's capabilities while respecting your users' preferences and existing choices.

---

What is LogTape?

LogTape is a logging library designed specifically for the modern JavaScript ecosystem. It stands out with its zero-dependency architecture, universal runtime support across Node.js, Deno, Bun, browsers, and edge functions, and a library-first design philosophy that allows library authors to add logging without imposing any burden on their users. When LogTape isn't configured, logging calls have virtually no performance impact, making it the only truly unobtrusive logging solution available.

For a comprehensive overview of LogTape's capabilities and philosophy, see our introduction guide.

Milestone achievement

We're excited to announce LogTape 1.0.0, marking a significant milestone in the library's development. This release represents our commitment to API stability and long-term support. The 1.0.0 designation signals that LogTape's core APIs are now stable and ready for production use, with any future breaking changes following semantic versioning principles.

This milestone builds upon months of refinement, community feedback, and real-world usage, establishing LogTape as a mature and reliable logging solution for JavaScript applications and libraries.

Major new features

High-performance logging infrastructure

LogTape 1.0.0 introduces several performance-oriented features designed for high-throughput production environments. The new non-blocking sink option allows console, stream, and file sinks to buffer log records and flush them asynchronously, preventing logging operations from blocking your application's main thread.

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: {
    console: getConsoleSink({ 
      nonBlocking: {
        bufferSize: 1000,
        flushInterval: 50
      }
    })
  },
  // ...
});

The new fromAsyncSink() function provides a clean way to integrate asynchronous logging operations while maintaining LogTape's synchronous sink interface. This enables scenarios like sending logs to remote servers or databases without blocking your application.

import { fromAsyncSink } from "@logtape/logtape";

const webhookSink = fromAsyncSink(async (record) => {
  await fetch("https://logs.example.com", {
    method: "POST",
    body: JSON.stringify(record)
  });
});

For file operations specifically, the new getStreamFileSink() function in the @logtape/file package leverages Node.js PassThrough streams to deliver optimal I/O performance with automatic backpressure management.

New sink integrations

This release significantly expands LogTape's integration capabilities with two major new sink packages. The @logtape/cloudwatch-logs package enables direct integration with AWS CloudWatch Logs, featuring intelligent batching, exponential backoff retry strategies, and support for structured logging through JSON Lines formatting.

import { getCloudWatchLogsSink } from "@logtape/cloudwatch-logs";

const sink = getCloudWatchLogsSink({
  logGroupName: "/aws/lambda/my-function",
  logStreamName: "my-stream",
  region: "us-east-1"
});

The @logtape/windows-eventlog package brings native Windows Event Log support with cross-runtime compatibility across Deno, Node.js, and Bun. This integration uses runtime-optimized FFI implementations for maximum performance while maintaining proper error handling and resource cleanup.

Beautiful development experience

The new @logtape/pretty package transforms console logging into a visually appealing experience designed specifically for local development. Inspired by Signale, it features colorful emojis for each log level, smart category truncation that preserves important context, and perfect column alignment that makes logs easy to scan.

import { configure, getConsoleSink } from "@logtape/logtape";
import { prettyFormatter } from "@logtape/pretty";

await configure({
  sinks: {
    console: getConsoleSink({ formatter: prettyFormatter })
  },
  // ...
});

As shown above, the pretty formatter supports true color terminals with rich color schemes, configurable icons, and intelligent word wrapping that maintains visual consistency even for long messages.

Ecosystem integration

Perhaps most significantly, LogTape 1.0.0 introduces adapter packages that bridge the gap between LogTape's library-friendly design and existing logging infrastructure. The @logtape/adaptor-winston and @logtape/adaptor-pino packages allow applications using these established logging libraries to seamlessly integrate LogTape-enabled libraries without changing their existing setup.

// Quick setup with winston
import "@logtape/adaptor-winston/install";

// Or with custom configuration
import { install } from "@logtape/adaptor-winston";
import winston from "winston";

const logger = winston.createLogger({/* your config */});
install(logger);

These adapters preserve LogTape's structured logging capabilities while routing everything through your preferred logging system, making adoption of LogTape-enabled libraries frictionless for existing applications.

Developer experience enhancements

This release includes several quality-of-life improvements for developers working with LogTape. The new getLogLevels() function provides programmatic access to all available log levels, while the LogMethod type offers better type inference for logging methods.

Browser compatibility has been improved, particularly for the @logtape/otel package, which previously had issues in browser environments due to Node.js-specific imports. The package now works seamlessly across all JavaScript runtimes without throwing module resolution errors.

Breaking changes and migration guide

LogTape 1.0.0 includes one notable breaking change: the removal of the deprecated LoggerConfig.level property. This property was deprecated in version 0.8.0 in favor of the more descriptive LoggerConfig.lowestLevel property.

If your configuration still uses the old property, simply rename it:

// Before (deprecated)
{ category: ["app"], level: "info", sinks: ["console"] }

// After
{ category: ["app"], lowestLevel: "info", sinks: ["console"] }

For more complex filtering requirements, consider using the LoggerConfig.filters option instead, which provides more flexibility and supports inheritance from parent loggers.

Complete package ecosystem

LogTape 1.0.0 represents the culmination of a comprehensive package ecosystem, now consisting of 11 specialized packages that address different aspects of logging infrastructure. This modular approach allows you to install only the packages you need, keeping your dependency footprint minimal while accessing powerful logging capabilities when required.

Package	JSR	npm	Description
@logtape/logtape	JSR	npm	Core logging functionality
@logtape/adaptor-pino	JSR	npm	Pino adapter
@logtape/adaptor-winston	JSR	npm	winston adapter
@logtape/cloudwatch-logs	JSR	npm	AWS CloudWatch Logs sink
@logtape/file	JSR	npm	File sinks
@logtape/otel	JSR	npm	OpenTelemetry sink
@logtape/pretty	JSR	npm	Beautiful text formatter
@logtape/redaction	JSR	npm	Data redaction
@logtape/sentry	JSR	npm	Sentry sink
@logtape/syslog	JSR	npm	Syslog sink
@logtape/windows-eventlog	JSR	npm	Windows Event Log sink

Getting started

Whether you're new to LogTape or upgrading from a previous version, getting started with 1.0.0 is straightforward. For new projects, begin with a simple configuration and gradually add the packages and features you need:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: "my-app", lowestLevel: "info", sinks: ["console"] }
  ]
});

Existing applications using winston or Pino can immediately benefit from LogTape-enabled libraries by installing the appropriate adapter. For comprehensive migration guidance and detailed feature documentation, visit our documentation site.

The 1.0.0 release represents not just a version number, but a commitment to the stability and maturity that production applications require. We're excited to see what you'll build with LogTape.

---

What is LogTape?

LogTape is a logging library designed specifically for the modern JavaScript ecosystem. It stands out with its zero-dependency architecture, universal runtime support across Node.js, Deno, Bun, browsers, and edge functions, and a library-first design philosophy that allows library authors to add logging without imposing any burden on their users. When LogTape isn't configured, logging calls have virtually no performance impact, making it the only truly unobtrusive logging solution available.

For a comprehensive overview of LogTape's capabilities and philosophy, see our introduction guide.

Milestone achievement

We're excited to announce LogTape 1.0.0, marking a significant milestone in the library's development. This release represents our commitment to API stability and long-term support. The 1.0.0 designation signals that LogTape's core APIs are now stable and ready for production use, with any future breaking changes following semantic versioning principles.

This milestone builds upon months of refinement, community feedback, and real-world usage, establishing LogTape as a mature and reliable logging solution for JavaScript applications and libraries.

Major new features

High-performance logging infrastructure

LogTape 1.0.0 introduces several performance-oriented features designed for high-throughput production environments. The new non-blocking sink option allows console, stream, and file sinks to buffer log records and flush them asynchronously, preventing logging operations from blocking your application's main thread.

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: {
    console: getConsoleSink({ 
      nonBlocking: {
        bufferSize: 1000,
        flushInterval: 50
      }
    })
  },
  // ...
});

The new fromAsyncSink() function provides a clean way to integrate asynchronous logging operations while maintaining LogTape's synchronous sink interface. This enables scenarios like sending logs to remote servers or databases without blocking your application.

import { fromAsyncSink } from "@logtape/logtape";

const webhookSink = fromAsyncSink(async (record) => {
  await fetch("https://logs.example.com", {
    method: "POST",
    body: JSON.stringify(record)
  });
});

For file operations specifically, the new getStreamFileSink() function in the @logtape/file package leverages Node.js PassThrough streams to deliver optimal I/O performance with automatic backpressure management.

New sink integrations

This release significantly expands LogTape's integration capabilities with two major new sink packages. The @logtape/cloudwatch-logs package enables direct integration with AWS CloudWatch Logs, featuring intelligent batching, exponential backoff retry strategies, and support for structured logging through JSON Lines formatting.

import { getCloudWatchLogsSink } from "@logtape/cloudwatch-logs";

const sink = getCloudWatchLogsSink({
  logGroupName: "/aws/lambda/my-function",
  logStreamName: "my-stream",
  region: "us-east-1"
});

The @logtape/windows-eventlog package brings native Windows Event Log support with cross-runtime compatibility across Deno, Node.js, and Bun. This integration uses runtime-optimized FFI implementations for maximum performance while maintaining proper error handling and resource cleanup.

Beautiful development experience

The new @logtape/pretty package transforms console logging into a visually appealing experience designed specifically for local development. Inspired by Signale, it features colorful emojis for each log level, smart category truncation that preserves important context, and perfect column alignment that makes logs easy to scan.

import { configure, getConsoleSink } from "@logtape/logtape";
import { prettyFormatter } from "@logtape/pretty";

await configure({
  sinks: {
    console: getConsoleSink({ formatter: prettyFormatter })
  },
  // ...
});

As shown above, the pretty formatter supports true color terminals with rich color schemes, configurable icons, and intelligent word wrapping that maintains visual consistency even for long messages.

Ecosystem integration

Perhaps most significantly, LogTape 1.0.0 introduces adapter packages that bridge the gap between LogTape's library-friendly design and existing logging infrastructure. The @logtape/adaptor-winston and @logtape/adaptor-pino packages allow applications using these established logging libraries to seamlessly integrate LogTape-enabled libraries without changing their existing setup.

// Quick setup with winston
import "@logtape/adaptor-winston/install";

// Or with custom configuration
import { install } from "@logtape/adaptor-winston";
import winston from "winston";

const logger = winston.createLogger({/* your config */});
install(logger);

These adapters preserve LogTape's structured logging capabilities while routing everything through your preferred logging system, making adoption of LogTape-enabled libraries frictionless for existing applications.

Developer experience enhancements

This release includes several quality-of-life improvements for developers working with LogTape. The new getLogLevels() function provides programmatic access to all available log levels, while the LogMethod type offers better type inference for logging methods.

Browser compatibility has been improved, particularly for the @logtape/otel package, which previously had issues in browser environments due to Node.js-specific imports. The package now works seamlessly across all JavaScript runtimes without throwing module resolution errors.

Breaking changes and migration guide

LogTape 1.0.0 includes one notable breaking change: the removal of the deprecated LoggerConfig.level property. This property was deprecated in version 0.8.0 in favor of the more descriptive LoggerConfig.lowestLevel property.

If your configuration still uses the old property, simply rename it:

// Before (deprecated)
{ category: ["app"], level: "info", sinks: ["console"] }

// After
{ category: ["app"], lowestLevel: "info", sinks: ["console"] }

For more complex filtering requirements, consider using the LoggerConfig.filters option instead, which provides more flexibility and supports inheritance from parent loggers.

Complete package ecosystem

LogTape 1.0.0 represents the culmination of a comprehensive package ecosystem, now consisting of 11 specialized packages that address different aspects of logging infrastructure. This modular approach allows you to install only the packages you need, keeping your dependency footprint minimal while accessing powerful logging capabilities when required.

Package	JSR	npm	Description
@logtape/logtape	JSR	npm	Core logging functionality
@logtape/adaptor-pino	JSR	npm	Pino adapter
@logtape/adaptor-winston	JSR	npm	winston adapter
@logtape/cloudwatch-logs	JSR	npm	AWS CloudWatch Logs sink
@logtape/file	JSR	npm	File sinks
@logtape/otel	JSR	npm	OpenTelemetry sink
@logtape/pretty	JSR	npm	Beautiful text formatter
@logtape/redaction	JSR	npm	Data redaction
@logtape/sentry	JSR	npm	Sentry sink
@logtape/syslog	JSR	npm	Syslog sink
@logtape/windows-eventlog	JSR	npm	Windows Event Log sink

Getting started

Whether you're new to LogTape or upgrading from a previous version, getting started with 1.0.0 is straightforward. For new projects, begin with a simple configuration and gradually add the packages and features you need:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: "my-app", lowestLevel: "info", sinks: ["console"] }
  ]
});

Existing applications using winston or Pino can immediately benefit from LogTape-enabled libraries by installing the appropriate adapter. For comprehensive migration guidance and detailed feature documentation, visit our documentation site.

The 1.0.0 release represents not just a version number, but a commitment to the stability and maturity that production applications require. We're excited to see what you'll build with LogTape.

---

What is LogTape?

LogTape is a logging library designed specifically for the modern JavaScript ecosystem. It stands out with its zero-dependency architecture, universal runtime support across Node.js, Deno, Bun, browsers, and edge functions, and a library-first design philosophy that allows library authors to add logging without imposing any burden on their users. When LogTape isn't configured, logging calls have virtually no performance impact, making it the only truly unobtrusive logging solution available.

For a comprehensive overview of LogTape's capabilities and philosophy, see our introduction guide.

Milestone achievement

We're excited to announce LogTape 1.0.0, marking a significant milestone in the library's development. This release represents our commitment to API stability and long-term support. The 1.0.0 designation signals that LogTape's core APIs are now stable and ready for production use, with any future breaking changes following semantic versioning principles.

This milestone builds upon months of refinement, community feedback, and real-world usage, establishing LogTape as a mature and reliable logging solution for JavaScript applications and libraries.

Major new features

High-performance logging infrastructure

LogTape 1.0.0 introduces several performance-oriented features designed for high-throughput production environments. The new non-blocking sink option allows console, stream, and file sinks to buffer log records and flush them asynchronously, preventing logging operations from blocking your application's main thread.

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: {
    console: getConsoleSink({ 
      nonBlocking: {
        bufferSize: 1000,
        flushInterval: 50
      }
    })
  },
  // ...
});

The new fromAsyncSink() function provides a clean way to integrate asynchronous logging operations while maintaining LogTape's synchronous sink interface. This enables scenarios like sending logs to remote servers or databases without blocking your application.

import { fromAsyncSink } from "@logtape/logtape";

const webhookSink = fromAsyncSink(async (record) => {
  await fetch("https://logs.example.com", {
    method: "POST",
    body: JSON.stringify(record)
  });
});

For file operations specifically, the new getStreamFileSink() function in the @logtape/file package leverages Node.js PassThrough streams to deliver optimal I/O performance with automatic backpressure management.

New sink integrations

This release significantly expands LogTape's integration capabilities with two major new sink packages. The @logtape/cloudwatch-logs package enables direct integration with AWS CloudWatch Logs, featuring intelligent batching, exponential backoff retry strategies, and support for structured logging through JSON Lines formatting.

import { getCloudWatchLogsSink } from "@logtape/cloudwatch-logs";

const sink = getCloudWatchLogsSink({
  logGroupName: "/aws/lambda/my-function",
  logStreamName: "my-stream",
  region: "us-east-1"
});

The @logtape/windows-eventlog package brings native Windows Event Log support with cross-runtime compatibility across Deno, Node.js, and Bun. This integration uses runtime-optimized FFI implementations for maximum performance while maintaining proper error handling and resource cleanup.

Beautiful development experience

The new @logtape/pretty package transforms console logging into a visually appealing experience designed specifically for local development. Inspired by Signale, it features colorful emojis for each log level, smart category truncation that preserves important context, and perfect column alignment that makes logs easy to scan.

import { configure, getConsoleSink } from "@logtape/logtape";
import { prettyFormatter } from "@logtape/pretty";

await configure({
  sinks: {
    console: getConsoleSink({ formatter: prettyFormatter })
  },
  // ...
});

As shown above, the pretty formatter supports true color terminals with rich color schemes, configurable icons, and intelligent word wrapping that maintains visual consistency even for long messages.

Ecosystem integration

Perhaps most significantly, LogTape 1.0.0 introduces adapter packages that bridge the gap between LogTape's library-friendly design and existing logging infrastructure. The @logtape/adaptor-winston and @logtape/adaptor-pino packages allow applications using these established logging libraries to seamlessly integrate LogTape-enabled libraries without changing their existing setup.

// Quick setup with winston
import "@logtape/adaptor-winston/install";

// Or with custom configuration
import { install } from "@logtape/adaptor-winston";
import winston from "winston";

const logger = winston.createLogger({/* your config */});
install(logger);

These adapters preserve LogTape's structured logging capabilities while routing everything through your preferred logging system, making adoption of LogTape-enabled libraries frictionless for existing applications.

Developer experience enhancements

This release includes several quality-of-life improvements for developers working with LogTape. The new getLogLevels() function provides programmatic access to all available log levels, while the LogMethod type offers better type inference for logging methods.

Browser compatibility has been improved, particularly for the @logtape/otel package, which previously had issues in browser environments due to Node.js-specific imports. The package now works seamlessly across all JavaScript runtimes without throwing module resolution errors.

Breaking changes and migration guide

LogTape 1.0.0 includes one notable breaking change: the removal of the deprecated LoggerConfig.level property. This property was deprecated in version 0.8.0 in favor of the more descriptive LoggerConfig.lowestLevel property.

If your configuration still uses the old property, simply rename it:

// Before (deprecated)
{ category: ["app"], level: "info", sinks: ["console"] }

// After
{ category: ["app"], lowestLevel: "info", sinks: ["console"] }

For more complex filtering requirements, consider using the LoggerConfig.filters option instead, which provides more flexibility and supports inheritance from parent loggers.

Complete package ecosystem

LogTape 1.0.0 represents the culmination of a comprehensive package ecosystem, now consisting of 11 specialized packages that address different aspects of logging infrastructure. This modular approach allows you to install only the packages you need, keeping your dependency footprint minimal while accessing powerful logging capabilities when required.

Package	JSR	npm	Description
@logtape/logtape	JSR	npm	Core logging functionality
@logtape/adaptor-pino	JSR	npm	Pino adapter
@logtape/adaptor-winston	JSR	npm	winston adapter
@logtape/cloudwatch-logs	JSR	npm	AWS CloudWatch Logs sink
@logtape/file	JSR	npm	File sinks
@logtape/otel	JSR	npm	OpenTelemetry sink
@logtape/pretty	JSR	npm	Beautiful text formatter
@logtape/redaction	JSR	npm	Data redaction
@logtape/sentry	JSR	npm	Sentry sink
@logtape/syslog	JSR	npm	Syslog sink
@logtape/windows-eventlog	JSR	npm	Windows Event Log sink

Getting started

Whether you're new to LogTape or upgrading from a previous version, getting started with 1.0.0 is straightforward. For new projects, begin with a simple configuration and gradually add the packages and features you need:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: "my-app", lowestLevel: "info", sinks: ["console"] }
  ]
});

Existing applications using winston or Pino can immediately benefit from LogTape-enabled libraries by installing the appropriate adapter. For comprehensive migration guidance and detailed feature documentation, visit our documentation site.

The 1.0.0 release represents not just a version number, but a commitment to the stability and maturity that production applications require. We're excited to see what you'll build with LogTape.

---

What is LogTape?

LogTape is a logging library designed specifically for the modern JavaScript ecosystem. It stands out with its zero-dependency architecture, universal runtime support across Node.js, Deno, Bun, browsers, and edge functions, and a library-first design philosophy that allows library authors to add logging without imposing any burden on their users. When LogTape isn't configured, logging calls have virtually no performance impact, making it the only truly unobtrusive logging solution available.

For a comprehensive overview of LogTape's capabilities and philosophy, see our introduction guide.

Milestone achievement

We're excited to announce LogTape 1.0.0, marking a significant milestone in the library's development. This release represents our commitment to API stability and long-term support. The 1.0.0 designation signals that LogTape's core APIs are now stable and ready for production use, with any future breaking changes following semantic versioning principles.

This milestone builds upon months of refinement, community feedback, and real-world usage, establishing LogTape as a mature and reliable logging solution for JavaScript applications and libraries.

Major new features

High-performance logging infrastructure

LogTape 1.0.0 introduces several performance-oriented features designed for high-throughput production environments. The new non-blocking sink option allows console, stream, and file sinks to buffer log records and flush them asynchronously, preventing logging operations from blocking your application's main thread.

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: {
    console: getConsoleSink({ 
      nonBlocking: {
        bufferSize: 1000,
        flushInterval: 50
      }
    })
  },
  // ...
});

The new fromAsyncSink() function provides a clean way to integrate asynchronous logging operations while maintaining LogTape's synchronous sink interface. This enables scenarios like sending logs to remote servers or databases without blocking your application.

import { fromAsyncSink } from "@logtape/logtape";

const webhookSink = fromAsyncSink(async (record) => {
  await fetch("https://logs.example.com", {
    method: "POST",
    body: JSON.stringify(record)
  });
});

For file operations specifically, the new getStreamFileSink() function in the @logtape/file package leverages Node.js PassThrough streams to deliver optimal I/O performance with automatic backpressure management.

New sink integrations

This release significantly expands LogTape's integration capabilities with two major new sink packages. The @logtape/cloudwatch-logs package enables direct integration with AWS CloudWatch Logs, featuring intelligent batching, exponential backoff retry strategies, and support for structured logging through JSON Lines formatting.

import { getCloudWatchLogsSink } from "@logtape/cloudwatch-logs";

const sink = getCloudWatchLogsSink({
  logGroupName: "/aws/lambda/my-function",
  logStreamName: "my-stream",
  region: "us-east-1"
});

The @logtape/windows-eventlog package brings native Windows Event Log support with cross-runtime compatibility across Deno, Node.js, and Bun. This integration uses runtime-optimized FFI implementations for maximum performance while maintaining proper error handling and resource cleanup.

Beautiful development experience

The new @logtape/pretty package transforms console logging into a visually appealing experience designed specifically for local development. Inspired by Signale, it features colorful emojis for each log level, smart category truncation that preserves important context, and perfect column alignment that makes logs easy to scan.

import { configure, getConsoleSink } from "@logtape/logtape";
import { prettyFormatter } from "@logtape/pretty";

await configure({
  sinks: {
    console: getConsoleSink({ formatter: prettyFormatter })
  },
  // ...
});

As shown above, the pretty formatter supports true color terminals with rich color schemes, configurable icons, and intelligent word wrapping that maintains visual consistency even for long messages.

Ecosystem integration

Perhaps most significantly, LogTape 1.0.0 introduces adapter packages that bridge the gap between LogTape's library-friendly design and existing logging infrastructure. The @logtape/adaptor-winston and @logtape/adaptor-pino packages allow applications using these established logging libraries to seamlessly integrate LogTape-enabled libraries without changing their existing setup.

// Quick setup with winston
import "@logtape/adaptor-winston/install";

// Or with custom configuration
import { install } from "@logtape/adaptor-winston";
import winston from "winston";

const logger = winston.createLogger({/* your config */});
install(logger);

These adapters preserve LogTape's structured logging capabilities while routing everything through your preferred logging system, making adoption of LogTape-enabled libraries frictionless for existing applications.

Developer experience enhancements

This release includes several quality-of-life improvements for developers working with LogTape. The new getLogLevels() function provides programmatic access to all available log levels, while the LogMethod type offers better type inference for logging methods.

Browser compatibility has been improved, particularly for the @logtape/otel package, which previously had issues in browser environments due to Node.js-specific imports. The package now works seamlessly across all JavaScript runtimes without throwing module resolution errors.

Breaking changes and migration guide

LogTape 1.0.0 includes one notable breaking change: the removal of the deprecated LoggerConfig.level property. This property was deprecated in version 0.8.0 in favor of the more descriptive LoggerConfig.lowestLevel property.

If your configuration still uses the old property, simply rename it:

// Before (deprecated)
{ category: ["app"], level: "info", sinks: ["console"] }

// After
{ category: ["app"], lowestLevel: "info", sinks: ["console"] }

For more complex filtering requirements, consider using the LoggerConfig.filters option instead, which provides more flexibility and supports inheritance from parent loggers.

Complete package ecosystem

LogTape 1.0.0 represents the culmination of a comprehensive package ecosystem, now consisting of 11 specialized packages that address different aspects of logging infrastructure. This modular approach allows you to install only the packages you need, keeping your dependency footprint minimal while accessing powerful logging capabilities when required.

Package	JSR	npm	Description
@logtape/logtape	JSR	npm	Core logging functionality
@logtape/adaptor-pino	JSR	npm	Pino adapter
@logtape/adaptor-winston	JSR	npm	winston adapter
@logtape/cloudwatch-logs	JSR	npm	AWS CloudWatch Logs sink
@logtape/file	JSR	npm	File sinks
@logtape/otel	JSR	npm	OpenTelemetry sink
@logtape/pretty	JSR	npm	Beautiful text formatter
@logtape/redaction	JSR	npm	Data redaction
@logtape/sentry	JSR	npm	Sentry sink
@logtape/syslog	JSR	npm	Syslog sink
@logtape/windows-eventlog	JSR	npm	Windows Event Log sink

Getting started

Whether you're new to LogTape or upgrading from a previous version, getting started with 1.0.0 is straightforward. For new projects, begin with a simple configuration and gradually add the packages and features you need:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: "my-app", lowestLevel: "info", sinks: ["console"] }
  ]
});

Existing applications using winston or Pino can immediately benefit from LogTape-enabled libraries by installing the appropriate adapter. For comprehensive migration guidance and detailed feature documentation, visit our documentation site.

The 1.0.0 release represents not just a version number, but a commitment to the stability and maturity that production applications require. We're excited to see what you'll build with LogTape.

---

What is LogTape?

LogTape is a logging library designed specifically for the modern JavaScript ecosystem. It stands out with its zero-dependency architecture, universal runtime support across Node.js, Deno, Bun, browsers, and edge functions, and a library-first design philosophy that allows library authors to add logging without imposing any burden on their users. When LogTape isn't configured, logging calls have virtually no performance impact, making it the only truly unobtrusive logging solution available.

For a comprehensive overview of LogTape's capabilities and philosophy, see our introduction guide.

Milestone achievement

We're excited to announce LogTape 1.0.0, marking a significant milestone in the library's development. This release represents our commitment to API stability and long-term support. The 1.0.0 designation signals that LogTape's core APIs are now stable and ready for production use, with any future breaking changes following semantic versioning principles.

This milestone builds upon months of refinement, community feedback, and real-world usage, establishing LogTape as a mature and reliable logging solution for JavaScript applications and libraries.

Major new features

High-performance logging infrastructure

LogTape 1.0.0 introduces several performance-oriented features designed for high-throughput production environments. The new non-blocking sink option allows console, stream, and file sinks to buffer log records and flush them asynchronously, preventing logging operations from blocking your application's main thread.

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: {
    console: getConsoleSink({ 
      nonBlocking: {
        bufferSize: 1000,
        flushInterval: 50
      }
    })
  },
  // ...
});

The new fromAsyncSink() function provides a clean way to integrate asynchronous logging operations while maintaining LogTape's synchronous sink interface. This enables scenarios like sending logs to remote servers or databases without blocking your application.

import { fromAsyncSink } from "@logtape/logtape";

const webhookSink = fromAsyncSink(async (record) => {
  await fetch("https://logs.example.com", {
    method: "POST",
    body: JSON.stringify(record)
  });
});

For file operations specifically, the new getStreamFileSink() function in the @logtape/file package leverages Node.js PassThrough streams to deliver optimal I/O performance with automatic backpressure management.

New sink integrations

This release significantly expands LogTape's integration capabilities with two major new sink packages. The @logtape/cloudwatch-logs package enables direct integration with AWS CloudWatch Logs, featuring intelligent batching, exponential backoff retry strategies, and support for structured logging through JSON Lines formatting.

import { getCloudWatchLogsSink } from "@logtape/cloudwatch-logs";

const sink = getCloudWatchLogsSink({
  logGroupName: "/aws/lambda/my-function",
  logStreamName: "my-stream",
  region: "us-east-1"
});

The @logtape/windows-eventlog package brings native Windows Event Log support with cross-runtime compatibility across Deno, Node.js, and Bun. This integration uses runtime-optimized FFI implementations for maximum performance while maintaining proper error handling and resource cleanup.

Beautiful development experience

The new @logtape/pretty package transforms console logging into a visually appealing experience designed specifically for local development. Inspired by Signale, it features colorful emojis for each log level, smart category truncation that preserves important context, and perfect column alignment that makes logs easy to scan.

import { configure, getConsoleSink } from "@logtape/logtape";
import { prettyFormatter } from "@logtape/pretty";

await configure({
  sinks: {
    console: getConsoleSink({ formatter: prettyFormatter })
  },
  // ...
});

As shown above, the pretty formatter supports true color terminals with rich color schemes, configurable icons, and intelligent word wrapping that maintains visual consistency even for long messages.

Ecosystem integration

Perhaps most significantly, LogTape 1.0.0 introduces adapter packages that bridge the gap between LogTape's library-friendly design and existing logging infrastructure. The @logtape/adaptor-winston and @logtape/adaptor-pino packages allow applications using these established logging libraries to seamlessly integrate LogTape-enabled libraries without changing their existing setup.

// Quick setup with winston
import "@logtape/adaptor-winston/install";

// Or with custom configuration
import { install } from "@logtape/adaptor-winston";
import winston from "winston";

const logger = winston.createLogger({/* your config */});
install(logger);

These adapters preserve LogTape's structured logging capabilities while routing everything through your preferred logging system, making adoption of LogTape-enabled libraries frictionless for existing applications.

Developer experience enhancements

This release includes several quality-of-life improvements for developers working with LogTape. The new getLogLevels() function provides programmatic access to all available log levels, while the LogMethod type offers better type inference for logging methods.

Browser compatibility has been improved, particularly for the @logtape/otel package, which previously had issues in browser environments due to Node.js-specific imports. The package now works seamlessly across all JavaScript runtimes without throwing module resolution errors.

Breaking changes and migration guide

LogTape 1.0.0 includes one notable breaking change: the removal of the deprecated LoggerConfig.level property. This property was deprecated in version 0.8.0 in favor of the more descriptive LoggerConfig.lowestLevel property.

If your configuration still uses the old property, simply rename it:

// Before (deprecated)
{ category: ["app"], level: "info", sinks: ["console"] }

// After
{ category: ["app"], lowestLevel: "info", sinks: ["console"] }

For more complex filtering requirements, consider using the LoggerConfig.filters option instead, which provides more flexibility and supports inheritance from parent loggers.

Complete package ecosystem

LogTape 1.0.0 represents the culmination of a comprehensive package ecosystem, now consisting of 11 specialized packages that address different aspects of logging infrastructure. This modular approach allows you to install only the packages you need, keeping your dependency footprint minimal while accessing powerful logging capabilities when required.

Package	JSR	npm	Description
@logtape/logtape	JSR	npm	Core logging functionality
@logtape/adaptor-pino	JSR	npm	Pino adapter
@logtape/adaptor-winston	JSR	npm	winston adapter
@logtape/cloudwatch-logs	JSR	npm	AWS CloudWatch Logs sink
@logtape/file	JSR	npm	File sinks
@logtape/otel	JSR	npm	OpenTelemetry sink
@logtape/pretty	JSR	npm	Beautiful text formatter
@logtape/redaction	JSR	npm	Data redaction
@logtape/sentry	JSR	npm	Sentry sink
@logtape/syslog	JSR	npm	Syslog sink
@logtape/windows-eventlog	JSR	npm	Windows Event Log sink

Getting started

Whether you're new to LogTape or upgrading from a previous version, getting started with 1.0.0 is straightforward. For new projects, begin with a simple configuration and gradually add the packages and features you need:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: "my-app", lowestLevel: "info", sinks: ["console"] }
  ]
});

Existing applications using winston or Pino can immediately benefit from LogTape-enabled libraries by installing the appropriate adapter. For comprehensive migration guidance and detailed feature documentation, visit our documentation site.

The 1.0.0 release represents not just a version number, but a commitment to the stability and maturity that production applications require. We're excited to see what you'll build with LogTape.

---

What is LogTape?

LogTape is a logging library designed specifically for the modern JavaScript ecosystem. It stands out with its zero-dependency architecture, universal runtime support across Node.js, Deno, Bun, browsers, and edge functions, and a library-first design philosophy that allows library authors to add logging without imposing any burden on their users. When LogTape isn't configured, logging calls have virtually no performance impact, making it the only truly unobtrusive logging solution available.

For a comprehensive overview of LogTape's capabilities and philosophy, see our introduction guide.

Milestone achievement

We're excited to announce LogTape 1.0.0, marking a significant milestone in the library's development. This release represents our commitment to API stability and long-term support. The 1.0.0 designation signals that LogTape's core APIs are now stable and ready for production use, with any future breaking changes following semantic versioning principles.

This milestone builds upon months of refinement, community feedback, and real-world usage, establishing LogTape as a mature and reliable logging solution for JavaScript applications and libraries.

Major new features

High-performance logging infrastructure

LogTape 1.0.0 introduces several performance-oriented features designed for high-throughput production environments. The new non-blocking sink option allows console, stream, and file sinks to buffer log records and flush them asynchronously, preventing logging operations from blocking your application's main thread.

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: {
    console: getConsoleSink({ 
      nonBlocking: {
        bufferSize: 1000,
        flushInterval: 50
      }
    })
  },
  // ...
});

The new fromAsyncSink() function provides a clean way to integrate asynchronous logging operations while maintaining LogTape's synchronous sink interface. This enables scenarios like sending logs to remote servers or databases without blocking your application.

import { fromAsyncSink } from "@logtape/logtape";

const webhookSink = fromAsyncSink(async (record) => {
  await fetch("https://logs.example.com", {
    method: "POST",
    body: JSON.stringify(record)
  });
});

For file operations specifically, the new getStreamFileSink() function in the @logtape/file package leverages Node.js PassThrough streams to deliver optimal I/O performance with automatic backpressure management.

New sink integrations

This release significantly expands LogTape's integration capabilities with two major new sink packages. The @logtape/cloudwatch-logs package enables direct integration with AWS CloudWatch Logs, featuring intelligent batching, exponential backoff retry strategies, and support for structured logging through JSON Lines formatting.

import { getCloudWatchLogsSink } from "@logtape/cloudwatch-logs";

const sink = getCloudWatchLogsSink({
  logGroupName: "/aws/lambda/my-function",
  logStreamName: "my-stream",
  region: "us-east-1"
});

The @logtape/windows-eventlog package brings native Windows Event Log support with cross-runtime compatibility across Deno, Node.js, and Bun. This integration uses runtime-optimized FFI implementations for maximum performance while maintaining proper error handling and resource cleanup.

Beautiful development experience

The new @logtape/pretty package transforms console logging into a visually appealing experience designed specifically for local development. Inspired by Signale, it features colorful emojis for each log level, smart category truncation that preserves important context, and perfect column alignment that makes logs easy to scan.

import { configure, getConsoleSink } from "@logtape/logtape";
import { prettyFormatter } from "@logtape/pretty";

await configure({
  sinks: {
    console: getConsoleSink({ formatter: prettyFormatter })
  },
  // ...
});

As shown above, the pretty formatter supports true color terminals with rich color schemes, configurable icons, and intelligent word wrapping that maintains visual consistency even for long messages.

Ecosystem integration

Perhaps most significantly, LogTape 1.0.0 introduces adapter packages that bridge the gap between LogTape's library-friendly design and existing logging infrastructure. The @logtape/adaptor-winston and @logtape/adaptor-pino packages allow applications using these established logging libraries to seamlessly integrate LogTape-enabled libraries without changing their existing setup.

// Quick setup with winston
import "@logtape/adaptor-winston/install";

// Or with custom configuration
import { install } from "@logtape/adaptor-winston";
import winston from "winston";

const logger = winston.createLogger({/* your config */});
install(logger);

These adapters preserve LogTape's structured logging capabilities while routing everything through your preferred logging system, making adoption of LogTape-enabled libraries frictionless for existing applications.

Developer experience enhancements

This release includes several quality-of-life improvements for developers working with LogTape. The new getLogLevels() function provides programmatic access to all available log levels, while the LogMethod type offers better type inference for logging methods.

Browser compatibility has been improved, particularly for the @logtape/otel package, which previously had issues in browser environments due to Node.js-specific imports. The package now works seamlessly across all JavaScript runtimes without throwing module resolution errors.

Breaking changes and migration guide

LogTape 1.0.0 includes one notable breaking change: the removal of the deprecated LoggerConfig.level property. This property was deprecated in version 0.8.0 in favor of the more descriptive LoggerConfig.lowestLevel property.

If your configuration still uses the old property, simply rename it:

// Before (deprecated)
{ category: ["app"], level: "info", sinks: ["console"] }

// After
{ category: ["app"], lowestLevel: "info", sinks: ["console"] }

For more complex filtering requirements, consider using the LoggerConfig.filters option instead, which provides more flexibility and supports inheritance from parent loggers.

Complete package ecosystem

LogTape 1.0.0 represents the culmination of a comprehensive package ecosystem, now consisting of 11 specialized packages that address different aspects of logging infrastructure. This modular approach allows you to install only the packages you need, keeping your dependency footprint minimal while accessing powerful logging capabilities when required.

Package	JSR	npm	Description
@logtape/logtape	JSR	npm	Core logging functionality
@logtape/adaptor-pino	JSR	npm	Pino adapter
@logtape/adaptor-winston	JSR	npm	winston adapter
@logtape/cloudwatch-logs	JSR	npm	AWS CloudWatch Logs sink
@logtape/file	JSR	npm	File sinks
@logtape/otel	JSR	npm	OpenTelemetry sink
@logtape/pretty	JSR	npm	Beautiful text formatter
@logtape/redaction	JSR	npm	Data redaction
@logtape/sentry	JSR	npm	Sentry sink
@logtape/syslog	JSR	npm	Syslog sink
@logtape/windows-eventlog	JSR	npm	Windows Event Log sink

Getting started

Whether you're new to LogTape or upgrading from a previous version, getting started with 1.0.0 is straightforward. For new projects, begin with a simple configuration and gradually add the packages and features you need:

import { configure, getConsoleSink } from "@logtape/logtape";

await configure({
  sinks: { console: getConsoleSink() },
  loggers: [
    { category: "my-app", lowestLevel: "info", sinks: ["console"] }
  ]
});

Existing applications using winston or Pino can immediately benefit from LogTape-enabled libraries by installing the appropriate adapter. For comprehensive migration guidance and detailed feature documentation, visit our documentation site.

The 1.0.0 release represents not just a version number, but a commitment to the stability and maturity that production applications require. We're excited to see what you'll build with LogTape.

---

LogTape is a zero-dependency logging library for JavaScript and TypeScript that provides a simple yet flexible logging system. It supports multiple JavaScript runtimes (Deno, Node.js, Bun, browsers, and edge functions), features hierarchical categories, structured logging, and offers seamless integration for both applications and libraries.

What's New in 0.12.0

Trace Log Level

LogTape now includes a trace severity level, which sits below debug in the verbosity hierarchy. This addition provides finer-grained control over logging output, particularly useful for detailed execution flow tracking during development and debugging.

• Added "trace" to the LogLevel union type
• Added Logger.trace() method for logging trace-level messages
• The complete severity hierarchy is now: trace < debug < info < warning < error < fatal

Enhanced File Sink Performance

File sinks now support configurable buffering, significantly improving write performance for high-volume logging scenarios.

• Added bufferSize option (default: 8192 characters) to control write buffering behavior
• Added flushInterval option (default: 5000ms) for automatic time-based buffer flushing
• Set bufferSize to 0 for immediate writes without buffering
• Set flushInterval to 0 to disable time-based flushing
• Buffer contents are automatically flushed when the sink is disposed

These options are available for both getFileSink() and getRotatingFileSink() functions.

Syslog Support

The new @logtape/syslog package enables sending log messages to syslog servers using the RFC 5424 format.

• Support for both UDP and TCP protocols
• All standard RFC 5424 facilities (kern, user, mail, daemon, local0–7, etc.)
• Automatic priority calculation based on log levels
• Structured data support for log record properties
• Cross-runtime compatibility with Deno, Node.js, and Bun
• Configurable connection timeouts, custom hostnames, and application names

Logger Method Alias

Added Logger.warning() as an alias for Logger.warn() to ensure consistency with the LogLevel type definition. This change addresses the naming mismatch where the LogLevel union type uses "warning" while the logger method was named warn(), making metaprogramming and dynamic method invocation more straightforward.

Unified Package Releases

Starting with version 0.12.0, all LogTape packages including @logtape/otel, @logtape/sentry, and @logtape/syslog share the same version number and are released together. This ensures compatibility between packages and simplifies version management for users.

Improved Build Infrastructure

LogTape has migrated from dnt to tsdown for npm package bundling. tsdown is a library-focused bundler built on top of Rolldown, a Rust-based bundler that powers the next generation of Vite. Unlike general-purpose bundlers, tsdown is specifically optimized for building TypeScript and JavaScript libraries with minimal configuration. This change brings several benefits:

• Elimination of bundler warnings in Webpack, Vite, and other build tools
• Improved compatibility with modern JavaScript toolchains
• Better tree-shaking support
• Cleaner package output
• Faster build times through Rust-based performance optimizations

Migration Guide

Updating to Trace Level

If you have code that relies on debug being the lowest severity level, you may need to update your log level configurations:

// Before
{ lowestLevel: "debug" }  // This was the most verbose setting

// After
{ lowestLevel: "trace" }  // Now includes trace messages

Leveraging Buffer Configuration

To optimize file sink performance in high-throughput scenarios:

getFileSink("app.log", {
  bufferSize: 16384,      // Larger buffer for better performance
  flushInterval: 10_000    // Flush every 10 seconds
})

Installation

LogTape 0.12.0 is available on JSR and npm:

deno add jsr:@logtape/logtape  # Deno
npm  add     @logtape/logtape  # npm
pnpm add     @logtape/logtape  # pnpm
yarn add     @logtape/logtape  # yarn
bun  add     @logtape/logtape  # Bun

For the syslog sink:

deno add jsr:@logtape/syslog  # Deno
npm  add     @logtape/syslog  # npm
pnpm add     @logtape/syslog  # pnpm
yarn add     @logtape/syslog  # yarn
bun  add     @logtape/syslog  # Bun

Acknowledgments

We thank all contributors who helped make this release possible, including those who reported issues, submitted pull requests, and provided feedback.

For the complete list of changes, please refer to the changelog.

---

LogTape is a zero-dependency logging library for JavaScript and TypeScript that provides a simple yet flexible logging system. It supports multiple JavaScript runtimes (Deno, Node.js, Bun, browsers, and edge functions), features hierarchical categories, structured logging, and offers seamless integration for both applications and libraries.

What's New in 0.12.0

Trace Log Level

LogTape now includes a trace severity level, which sits below debug in the verbosity hierarchy. This addition provides finer-grained control over logging output, particularly useful for detailed execution flow tracking during development and debugging.

• Added "trace" to the LogLevel union type
• Added Logger.trace() method for logging trace-level messages
• The complete severity hierarchy is now: trace < debug < info < warning < error < fatal

Enhanced File Sink Performance

File sinks now support configurable buffering, significantly improving write performance for high-volume logging scenarios.

• Added bufferSize option (default: 8192 characters) to control write buffering behavior
• Added flushInterval option (default: 5000ms) for automatic time-based buffer flushing
• Set bufferSize to 0 for immediate writes without buffering
• Set flushInterval to 0 to disable time-based flushing
• Buffer contents are automatically flushed when the sink is disposed

These options are available for both getFileSink() and getRotatingFileSink() functions.

Syslog Support

The new @logtape/syslog package enables sending log messages to syslog servers using the RFC 5424 format.

• Support for both UDP and TCP protocols
• All standard RFC 5424 facilities (kern, user, mail, daemon, local0–7, etc.)
• Automatic priority calculation based on log levels
• Structured data support for log record properties
• Cross-runtime compatibility with Deno, Node.js, and Bun
• Configurable connection timeouts, custom hostnames, and application names

Logger Method Alias

Added Logger.warning() as an alias for Logger.warn() to ensure consistency with the LogLevel type definition. This change addresses the naming mismatch where the LogLevel union type uses "warning" while the logger method was named warn(), making metaprogramming and dynamic method invocation more straightforward.

Unified Package Releases

Starting with version 0.12.0, all LogTape packages including @logtape/otel, @logtape/sentry, and @logtape/syslog share the same version number and are released together. This ensures compatibility between packages and simplifies version management for users.

Improved Build Infrastructure

LogTape has migrated from dnt to tsdown for npm package bundling. tsdown is a library-focused bundler built on top of Rolldown, a Rust-based bundler that powers the next generation of Vite. Unlike general-purpose bundlers, tsdown is specifically optimized for building TypeScript and JavaScript libraries with minimal configuration. This change brings several benefits:

• Elimination of bundler warnings in Webpack, Vite, and other build tools
• Improved compatibility with modern JavaScript toolchains
• Better tree-shaking support
• Cleaner package output
• Faster build times through Rust-based performance optimizations

Migration Guide

Updating to Trace Level

If you have code that relies on debug being the lowest severity level, you may need to update your log level configurations:

// Before
{ lowestLevel: "debug" }  // This was the most verbose setting

// After
{ lowestLevel: "trace" }  // Now includes trace messages

Leveraging Buffer Configuration

To optimize file sink performance in high-throughput scenarios:

getFileSink("app.log", {
  bufferSize: 16384,      // Larger buffer for better performance
  flushInterval: 10_000    // Flush every 10 seconds
})

Installation

LogTape 0.12.0 is available on JSR and npm:

deno add jsr:@logtape/logtape  # Deno
npm  add     @logtape/logtape  # npm
pnpm add     @logtape/logtape  # pnpm
yarn add     @logtape/logtape  # yarn
bun  add     @logtape/logtape  # Bun

For the syslog sink:

deno add jsr:@logtape/syslog  # Deno
npm  add     @logtape/syslog  # npm
pnpm add     @logtape/syslog  # pnpm
yarn add     @logtape/syslog  # yarn
bun  add     @logtape/syslog  # Bun

Acknowledgments

We thank all contributors who helped make this release possible, including those who reported issues, submitted pull requests, and provided feedback.

For the complete list of changes, please refer to the changelog.

---

LogTape is a zero-dependency logging library for JavaScript and TypeScript that provides a simple yet flexible logging system. It supports multiple JavaScript runtimes (Deno, Node.js, Bun, browsers, and edge functions), features hierarchical categories, structured logging, and offers seamless integration for both applications and libraries.

What's New in 0.12.0

Trace Log Level

LogTape now includes a trace severity level, which sits below debug in the verbosity hierarchy. This addition provides finer-grained control over logging output, particularly useful for detailed execution flow tracking during development and debugging.

• Added "trace" to the LogLevel union type
• Added Logger.trace() method for logging trace-level messages
• The complete severity hierarchy is now: trace < debug < info < warning < error < fatal

Enhanced File Sink Performance

File sinks now support configurable buffering, significantly improving write performance for high-volume logging scenarios.

• Added bufferSize option (default: 8192 characters) to control write buffering behavior
• Added flushInterval option (default: 5000ms) for automatic time-based buffer flushing
• Set bufferSize to 0 for immediate writes without buffering
• Set flushInterval to 0 to disable time-based flushing
• Buffer contents are automatically flushed when the sink is disposed

These options are available for both getFileSink() and getRotatingFileSink() functions.

Syslog Support

The new @logtape/syslog package enables sending log messages to syslog servers using the RFC 5424 format.

• Support for both UDP and TCP protocols
• All standard RFC 5424 facilities (kern, user, mail, daemon, local0–7, etc.)
• Automatic priority calculation based on log levels
• Structured data support for log record properties
• Cross-runtime compatibility with Deno, Node.js, and Bun
• Configurable connection timeouts, custom hostnames, and application names

Logger Method Alias

Added Logger.warning() as an alias for Logger.warn() to ensure consistency with the LogLevel type definition. This change addresses the naming mismatch where the LogLevel union type uses "warning" while the logger method was named warn(), making metaprogramming and dynamic method invocation more straightforward.

Unified Package Releases

Starting with version 0.12.0, all LogTape packages including @logtape/otel, @logtape/sentry, and @logtape/syslog share the same version number and are released together. This ensures compatibility between packages and simplifies version management for users.

Improved Build Infrastructure

LogTape has migrated from dnt to tsdown for npm package bundling. tsdown is a library-focused bundler built on top of Rolldown, a Rust-based bundler that powers the next generation of Vite. Unlike general-purpose bundlers, tsdown is specifically optimized for building TypeScript and JavaScript libraries with minimal configuration. This change brings several benefits:

• Elimination of bundler warnings in Webpack, Vite, and other build tools
• Improved compatibility with modern JavaScript toolchains
• Better tree-shaking support
• Cleaner package output
• Faster build times through Rust-based performance optimizations

Migration Guide

Updating to Trace Level

If you have code that relies on debug being the lowest severity level, you may need to update your log level configurations:

// Before
{ lowestLevel: "debug" }  // This was the most verbose setting

// After
{ lowestLevel: "trace" }  // Now includes trace messages

Leveraging Buffer Configuration

To optimize file sink performance in high-throughput scenarios:

getFileSink("app.log", {
  bufferSize: 16384,      // Larger buffer for better performance
  flushInterval: 10_000    // Flush every 10 seconds
})

Installation

LogTape 0.12.0 is available on JSR and npm:

deno add jsr:@logtape/logtape  # Deno
npm  add     @logtape/logtape  # npm
pnpm add     @logtape/logtape  # pnpm
yarn add     @logtape/logtape  # yarn
bun  add     @logtape/logtape  # Bun

For the syslog sink:

deno add jsr:@logtape/syslog  # Deno
npm  add     @logtape/syslog  # npm
pnpm add     @logtape/syslog  # pnpm
yarn add     @logtape/syslog  # yarn
bun  add     @logtape/syslog  # Bun

Acknowledgments

We thank all contributors who helped make this release possible, including those who reported issues, submitted pull requests, and provided feedback.

For the complete list of changes, please refer to the changelog.

---

LogTape is a zero-dependency logging library for JavaScript and TypeScript that provides a simple yet flexible logging system. It supports multiple JavaScript runtimes (Deno, Node.js, Bun, browsers, and edge functions), features hierarchical categories, structured logging, and offers seamless integration for both applications and libraries.

What's New in 0.12.0

Trace Log Level

LogTape now includes a trace severity level, which sits below debug in the verbosity hierarchy. This addition provides finer-grained control over logging output, particularly useful for detailed execution flow tracking during development and debugging.

• Added "trace" to the LogLevel union type
• Added Logger.trace() method for logging trace-level messages
• The complete severity hierarchy is now: trace < debug < info < warning < error < fatal

Enhanced File Sink Performance

File sinks now support configurable buffering, significantly improving write performance for high-volume logging scenarios.

• Added bufferSize option (default: 8192 characters) to control write buffering behavior
• Added flushInterval option (default: 5000ms) for automatic time-based buffer flushing
• Set bufferSize to 0 for immediate writes without buffering
• Set flushInterval to 0 to disable time-based flushing
• Buffer contents are automatically flushed when the sink is disposed

These options are available for both getFileSink() and getRotatingFileSink() functions.

Syslog Support

The new @logtape/syslog package enables sending log messages to syslog servers using the RFC 5424 format.

• Support for both UDP and TCP protocols
• All standard RFC 5424 facilities (kern, user, mail, daemon, local0–7, etc.)
• Automatic priority calculation based on log levels
• Structured data support for log record properties
• Cross-runtime compatibility with Deno, Node.js, and Bun
• Configurable connection timeouts, custom hostnames, and application names

Logger Method Alias

Added Logger.warning() as an alias for Logger.warn() to ensure consistency with the LogLevel type definition. This change addresses the naming mismatch where the LogLevel union type uses "warning" while the logger method was named warn(), making metaprogramming and dynamic method invocation more straightforward.

Unified Package Releases

Starting with version 0.12.0, all LogTape packages including @logtape/otel, @logtape/sentry, and @logtape/syslog share the same version number and are released together. This ensures compatibility between packages and simplifies version management for users.

Improved Build Infrastructure

LogTape has migrated from dnt to tsdown for npm package bundling. tsdown is a library-focused bundler built on top of Rolldown, a Rust-based bundler that powers the next generation of Vite. Unlike general-purpose bundlers, tsdown is specifically optimized for building TypeScript and JavaScript libraries with minimal configuration. This change brings several benefits:

• Elimination of bundler warnings in Webpack, Vite, and other build tools
• Improved compatibility with modern JavaScript toolchains
• Better tree-shaking support
• Cleaner package output
• Faster build times through Rust-based performance optimizations

Migration Guide

Updating to Trace Level

If you have code that relies on debug being the lowest severity level, you may need to update your log level configurations:

// Before
{ lowestLevel: "debug" }  // This was the most verbose setting

// After
{ lowestLevel: "trace" }  // Now includes trace messages

Leveraging Buffer Configuration

To optimize file sink performance in high-throughput scenarios:

getFileSink("app.log", {
  bufferSize: 16384,      // Larger buffer for better performance
  flushInterval: 10_000    // Flush every 10 seconds
})

Installation

LogTape 0.12.0 is available on JSR and npm:

deno add jsr:@logtape/logtape  # Deno
npm  add     @logtape/logtape  # npm
pnpm add     @logtape/logtape  # pnpm
yarn add     @logtape/logtape  # yarn
bun  add     @logtape/logtape  # Bun

For the syslog sink:

deno add jsr:@logtape/syslog  # Deno
npm  add     @logtape/syslog  # npm
pnpm add     @logtape/syslog  # pnpm
yarn add     @logtape/syslog  # yarn
bun  add     @logtape/syslog  # Bun

Acknowledgments

We thank all contributors who helped make this release possible, including those who reported issues, submitted pull requests, and provided feedback.

For the complete list of changes, please refer to the changelog.