@fedify@hollo.social · 8 following · 743 followers
Fedify is a TypeScript library for building federated server apps powered by ActivityPub and other standards, so-called fediverse. It aims to eliminate the complexity and redundant boilerplate code when building a federated server app, so that you can focus on your business logic and user experience.
@fedify@hollo.social
🎉 Excited to announce that #Fedify is now on Open Collective! Support the project's development starting at:
Your support will help us maintain and improve Fedify. Check it out here:
https://opencollective.com/fedify
@fedify@hollo.social
Fedify is an #ActivityPub server framework in #TypeScript & #JavaScript. It aims to eliminate the complexity and redundant boilerplate code when building a federated server app, so that you can focus on your business logic and user experience.
The key features it provides currently are:
If you're curious, take a look at the #Fedify website! There's comprehensive docs, a demo, a tutorial, example code, and more:
@hongminhee@hollo.social
I've been thinking about adding a debug dashboard to #Fedify that shows all #ActivityPub activities being sent and received in real-time. This would include filters by activity type, detailed inspection of JSON-LD content, signature verification details, and retry management for failed deliveries.
As a #fedidev, would you find this useful for troubleshooting federation issues? Any other features that would be helpful in such a debugging tool?
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
Fedifyとは？Fedifyは、ActivityPubベースのフェデレーションサーバーフレームワークで、開発者が分散型ソーシャルネットワークである#フェディバース（#fediverse）にアプリケーションを簡単に統合できるよう支援します。複雑なActivityPubプロトコルの実装を簡素化し、開発時間を大幅に短縮します。MITライセンスの下で提供されるオープンソースプロジェクトです。
すでに様々なプロジェクトがFedifyを活用しています：
ActivityPubの実装をご検討中の方や、Fedifyプロジェクトとの協力にご興味のある方は、ぜひご連絡ください：
お客様の要件と目標に合わせたカスタマイズされた協力の可能性を一緒に探りましょう。
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
Fedify란?Fedify는 #ActivityPub 기반 연합형 서버 프레임워크로, 개발자들이 분산형 소셜 네트워크인 #연합우주(#fediverse)에 애플리케이션을 쉽게 통합할 수 있도록 돕습니다. 복잡한 ActivityPub 프로토콜 구현을 단순화하여 개발 시간을 크게 단축시킵니다. MIT 라이선스 하에 제공되는 오픈 소스 프로젝트입니다.
다양한 프로젝트들이 이미 Fedify를 활용하고 있습니다:
ActivityPub 구현을 고려 중이시거나, Fedify 프로젝트와 협력하고 싶으시다면 연락 주세요:
귀사의 요구사항과 목표에 맞는 맞춤형 협력 방안을 함께 모색하겠습니다.
@fedify@hollo.social
What is Fedify?#Fedify is an #ActivityPub-based federated server framework that helps developers easily integrate their applications with the #fediverse, a decentralized social network. It simplifies the complex implementation of the ActivityPub protocol, significantly reducing development time. Fedify is an open-source project available under the MIT license.
Various projects are already leveraging Fedify:
If you're considering implementing ActivityPub or wish to collaborate with the Fedify project, please get in touch:
We're excited to explore customized collaboration opportunities that align with your requirements and goals.
@hongminhee@hollo.social · Reply to 洪 民憙 (Hong Minhee)'s post
For those interested in supporting #Fedify's development, we do have an Open Collective page where community #sponsorship is welcome.
Even small contributions help sustain development and show there's interest in open source #ActivityPub tools. Thanks to our existing sponsors who've already been helping move the project forward!
The goal remains the same: make building federated applications more accessible to developers so the #fediverse can continue to grow and thrive.
@hongminhee@hollo.social
Just received word that @fedify wasn't selected for @nlnet's Open Call this round. While disappointing, I understand the competition was fierce with many worthy projects seeking limited funding.
The journey continues though—#Fedify development will move forward at its own pace. Thanks to everyone who's shown interest and support for this project so far. Building tools for the #fediverse remains important work, and I'm committed to seeing it through.
If you know of other funding opportunities that might be a good fit for open source #ActivityPub tools, I'm all ears.
@fedify@hollo.social
Good news! We've officially added #Cloudflare #Workers support to the #Fedify roadmap. We've created a detailed issue to track our implementation plan: https://github.com/fedify-dev/fedify/issues/233.
The effort will be tackled in phases, including compatibility assessment, core adaptations for Workers' environment, KV store and message queue implementations, and finally integration with Cloudflare's ecosystem. This will be a substantial project that we'll break down into several sub-issues.
If you're interested in contributing to any specific aspect of Workers support, please comment on the main issue to coordinate efforts.
🍆@Yohei_Zuho@mstdn.y-zu.org
Fedify本、TPM入稿だん！
@hongminhee@hollo.social · Reply to 洪 民憙 (Hong Minhee)'s post
Okay, I've just deployed a bleeding edge #Fedify, which implements both RFC 9421 and double-knocking, to Hackers' Pub. If you'd like to test your implementations against a real server, please give it a try! (If you want to create an account, let me know—I can invite you.)
@hongminhee@hollo.social
Looking for #ActivityPub implementations with #RFC9421 support! 🔍
As mentioned in the Fedify announcement below, I've implemented RFC 9421 (HTTP Message Signatures) and need to verify its interoperability with other ActivityPub implementations.
The challenge is that most major ActivityPub projects don't seem to have full RFC 9421 implementations in production yet. If you're working on an ActivityPub project that:
Please reach out! I'd love to collaborate on interoperability testing to ensure our implementations work properly with each other before merging this into #Fedify's main branch.
Any leads or connections would be greatly appreciated! 🙏
@fedify@hollo.social
We're excited to announce that we've implemented RFC 9421 (HTTP Message Signatures) in #Fedify, complete with our double-knocking mechanism to maintain backward compatibility with the draft cavage version.
This implementation includes both signature generation and verification, meaning #RFC9421 is used when both sending and receiving activities. While we haven't merged the RFC 9421 implementation branch yet, we're currently conducting interoperability tests with development versions of Mastodon and other #ActivityPub implementations. Once these tests confirm compatibility, we'll proceed with the merge.
As noted in the attached docs, although RFC 9421 is the final and official standard for HTTP Signatures, the draft cavage version remains widely used across the #fediverse. Our double-knocking mechanism ensures maximum compatibility by trying the RFC 9421 version first, then falling back to draft cavage if needed.
Currently, we support RSA-PKCS#1-v1.5 key pairs for generating HTTP Message Signatures, with plans to expand to other signature types in future releases.
We look forward to contributing to a more standardized and secure fediverse!
@fedify@hollo.social
We're excited to announce that we've implemented RFC 9421 (HTTP Message Signatures) in #Fedify, complete with our double-knocking mechanism to maintain backward compatibility with the draft cavage version.
This implementation includes both signature generation and verification, meaning #RFC9421 is used when both sending and receiving activities. While we haven't merged the RFC 9421 implementation branch yet, we're currently conducting interoperability tests with development versions of Mastodon and other #ActivityPub implementations. Once these tests confirm compatibility, we'll proceed with the merge.
As noted in the attached docs, although RFC 9421 is the final and official standard for HTTP Signatures, the draft cavage version remains widely used across the #fediverse. Our double-knocking mechanism ensures maximum compatibility by trying the RFC 9421 version first, then falling back to draft cavage if needed.
Currently, we support RSA-PKCS#1-v1.5 key pairs for generating HTTP Message Signatures, with plans to expand to other signature types in future releases.
We look forward to contributing to a more standardized and secure fediverse!
@fedify@hollo.social
We're pleased to announce that #Fedify has been included in the Nivenly Fediverse Security Fund program!
The @nivenly Foundation has launched a security bounty fund to support contributors who identify and help fix #security vulnerabilities in popular #fediverse software. Both Fedify and @hollo are among the selected projects that meet their responsible security disclosure requirements.
This program will run from April–September 2025, with bounties of $250–$500 USD for high and critical security vulnerabilities.
We're honored to be recognized alongside other established fediverse projects like Mastodon, Misskey, and Lemmy. This further encourages our commitment to maintaining strong security practices.
If you're interested in contributing to Fedify's security, please follow our responsible disclosure process outlined in our SECURITY.md file.
Learn more about the program:
https://nivenly.org/blog/2025/04/01/nivenly-fediverse-security-fund/
@nborboen@social.epfl.ch
What to learn more about the #fediverse and #ActivityPub? This tutorial (https://fedify.dev/tutorial/microblog) from @fedify is a really good starter. It explains how to implement a really simple #federated server and see how communication exchange are done with AP.
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
もしかしたらご存じないかもしれませんが、Fedifyには DiscordとMatrixのコミュニティがあります。ここでは、サポートを受けたり、機能について議論したり、ActivityPubやフェデレーテッドソーシャルネットワークについて話し合うことができます。
お好みのコミュニティにご参加ください。どちらのチャンネルでも、Fedifyやフェデレーション関連のトピックについて活発な議論が行われています。
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
혹시 모르고 계셨다면, Fedify는 Discord와 Matrix 커뮤니티를 운영하고 있습니다. 이곳에서 도움을 받거나, 기능에 대해 논의하거나, ActivityPub와 연합 소셜 네트워크에 대해 대화를 나눌 수 있습니다.
여러분의 선호도에 따라 어느 커뮤니티든 참여해 주세요. 두 채널 모두 Fedify와 연합 관련 주제에 대한 활발한 논의가 이루어지고 있습니다.
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
自分だけのActivityPubを作りたいけど、何から始めれば良いのか分からないですか？Fedifyの公式チュートリアル「自分だけのフェディバースのマイクロブログを作ろう！」を読んでみてください！
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
자신만의 #ActivityPub 구현을 하고 싶지만, 어디서 시작해야 할지 모르겠나요? #Fedify 공식 튜토리얼인 〈나만의 연합우주 마이크로블로그 만들기〉를 읽고 따라해 보세요!
@basus@mastodon.social
I should suck it up and learn to program properly in TypeScript. There's a growing list of software that I'd like to use and extend that uses TypeScript (Obsidian, Lume, Fedify), not to mention its utility for web programming. The language itself is pretty good, though I'm not thrilled by a lot of the tooling and ecosystem around it. Hopefully there's a way of writing usable code in it that keeps the messiness at bay.
@fedify@hollo.social
Want to build your own #ActivityPub implementation, but don't know where to start? Read and follow #Fedify's official tutorial, Creating your own federated microblog, and get started!
@fedify@hollo.social
📣 Exciting news! Fedify CLI is now available via Homebrew!
If you're using #Homebrew on macOS or #Linuxbrew on Linux, you can now install our CLI toolchain with a simple command:
brew install fedify
This makes it even easier to get started with building your federated server app. Try it out and let us know what you think!
@geeknews_bot@sns.lemondouble.com
Show GN: 나만의 연합우주(fediverse) 마이크로블로그 만들기
------------------------------
이 튜토리얼은 [Fedify] 라이브러리를 사용하여 [ActivityPub] 프로토콜 기반의 마이크로블로그 서비스를 구현하는 방법을 설명합니다. ActivityPub은 다양한 소셜 네트워크 서비스들이 서로 연동될 수 있게 해주는 분산형 소셜 네트워킹 프로토콜로, 이를 통해 [Mastodon], [Misskey] 같은 서비스와 상호작용할 수 있는 독…
------------------------------
https://news.hada.io/topic?id=20508&utm_source=googlechat&utm_medium=bot&utm_campaign=1834
@hkrn@mstdn.social
Creating your own federated microblog
L: https://fedify.dev/tutorial/microblog
C: https://news.ycombinator.com/item?id=43780785
posted on 2025.04.24 at 05:37:57 (c=0, p=8)
@fedify@hollo.social
Hey folks! We're excited to share a preview of a new API coming in #Fedify 1.6 that should make structuring larger federated apps much cleaner: FederationBuilder.
As your Fedify applications grow, you might encounter circular dependency issues when registering dispatchers and listeners across multiple files. The new FederationBuilder pattern helps solve this by separating the configuration phase from instantiation.
Instead of this:
// federation.ts
import { createFederation } from "@fedify/fedify";
export const federation = createFederation<AppContext>({
kv: new DbKvStore(),
queue: new RedisMessageQueue(),
// Other options...
});
// Now we need to import this federation instance in other files
// to register dispatchers and listeners...
You can now do this:
// builder.ts
import { createFederationBuilder } from "@fedify/fedify";
export const builder = createFederationBuilder<AppContext>();
// other files can import and configure this builder...
// actors.ts
import { builder } from "./builder.ts";
import { Person } from "@fedify/fedify";
builder.setActorDispatcher("/users/{handle}", async (ctx, handle) => {
// Actor implementation
});
// inbox.ts
import { builder } from "./builder.ts";
import { Follow } from "@fedify/fedify";
builder.setInboxListeners("/users/{handle}/inbox", "/inbox")
.on(Follow, async (ctx, follow) => {
// Follow handling
});
// main.ts — Only create the Federation instance at startup
import { builder } from "./builder.ts";
// Build the Federation object with actual dependencies
export const federation = await builder.build({
kv: new DbKvStore(),
queue: new RedisMessageQueue(),
// Other options...
});
This pattern helps avoid circular dependencies and makes your code more modular. Each part of your app can configure the builder without needing the actual Federation instance.
The full documentation will be available when 1.6 is released, but we wanted to share this early with our community. Looking forward to your feedback when it lands!
Want to try it right now? You can install the development version from JSR or npm:
# Deno
deno add jsr:@fedify/fedify@1.6.0-dev.777+1206cb01
# Node.js
npm add @fedify/fedify@1.6.0-dev.777
# Bun
bun add @fedify/fedify@1.6.0-dev.777
@fedify@hollo.social
Hey folks! We're excited to share a preview of a new API coming in #Fedify 1.6 that should make structuring larger federated apps much cleaner: FederationBuilder.
As your Fedify applications grow, you might encounter circular dependency issues when registering dispatchers and listeners across multiple files. The new FederationBuilder pattern helps solve this by separating the configuration phase from instantiation.
Instead of this:
// federation.ts
import { createFederation } from "@fedify/fedify";
export const federation = createFederation<AppContext>({
kv: new DbKvStore(),
queue: new RedisMessageQueue(),
// Other options...
});
// Now we need to import this federation instance in other files
// to register dispatchers and listeners...
You can now do this:
// builder.ts
import { createFederationBuilder } from "@fedify/fedify";
export const builder = createFederationBuilder<AppContext>();
// other files can import and configure this builder...
// actors.ts
import { builder } from "./builder.ts";
import { Person } from "@fedify/fedify";
builder.setActorDispatcher("/users/{handle}", async (ctx, handle) => {
// Actor implementation
});
// inbox.ts
import { builder } from "./builder.ts";
import { Follow } from "@fedify/fedify";
builder.setInboxListeners("/users/{handle}/inbox", "/inbox")
.on(Follow, async (ctx, follow) => {
// Follow handling
});
// main.ts — Only create the Federation instance at startup
import { builder } from "./builder.ts";
// Build the Federation object with actual dependencies
export const federation = await builder.build({
kv: new DbKvStore(),
queue: new RedisMessageQueue(),
// Other options...
});
This pattern helps avoid circular dependencies and makes your code more modular. Each part of your app can configure the builder without needing the actual Federation instance.
The full documentation will be available when 1.6 is released, but we wanted to share this early with our community. Looking forward to your feedback when it lands!
Want to try it right now? You can install the development version from JSR or npm:
# Deno
deno add jsr:@fedify/fedify@1.6.0-dev.777+1206cb01
# Node.js
npm add @fedify/fedify@1.6.0-dev.777
# Bun
bun add @fedify/fedify@1.6.0-dev.777
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
もしかしたらご存じないかもしれませんが、Fedifyには DiscordとMatrixのコミュニティがあります。ここでは、サポートを受けたり、機能について議論したり、ActivityPubやフェデレーテッドソーシャルネットワークについて話し合うことができます。
お好みのコミュニティにご参加ください。どちらのチャンネルでも、Fedifyやフェデレーション関連のトピックについて活発な議論が行われています。
@fedify@hollo.social · Reply to Fedify: an ActivityPub server framework's post
혹시 모르고 계셨다면, Fedify는 Discord와 Matrix 커뮤니티를 운영하고 있습니다. 이곳에서 도움을 받거나, 기능에 대해 논의하거나, ActivityPub와 연합 소셜 네트워크에 대해 대화를 나눌 수 있습니다.
여러분의 선호도에 따라 어느 커뮤니티든 참여해 주세요. 두 채널 모두 Fedify와 연합 관련 주제에 대한 활발한 논의가 이루어지고 있습니다.
@fedify@hollo.social
In case you weren't aware, #Fedify has both #Discord and #Matrix communities where you can get help, discuss features, or just chat about #ActivityPub and federated social networks.
Feel free to join either community based on your preference. Both channels have active discussions about Fedify and federation topics.
@almosterick@mastodon.social
We at @index@www.avant.dev have contributed to @fedify - the framework enabling @index@activitypub.ghost.org integration with the fediverse.
As social networks build walls, Fedify creates critical infrastructure for an open web. Their tools simplify federation protocols, making decentralized communication accessible.
Support: https://opencollective.com/fedify
@kodingwarrior@silicon.moe
뭔가 이거 만들다보니까 fedify를 이용한 sns 만들기 스타터킷 같은게 만들어지면 좋을 것 같음.
* 노트 작성
* 팔로/언팔
* 타임라인
* 프로필
* 블락/블락해제
이런 것들이 미리 구현은 되어있고 나머지 기능은 요령껏 채우면 되는
@hongminhee@hollo.social
Don't build #ActivityPub from scratch! It's complex. See why using the #Fedify framework is the smarter way to develop for the fediverse in my new post:
@hongminhee@hackers.pub
So, you're captivated by the fediverse—the decentralized social web powered by protocols like ActivityPub. Maybe you're dreaming of building the next great federated app, a unique space connected to Mastodon, Lemmy, Pixelfed, and more. The temptation to dive deep and implement ActivityPub yourself, from the ground up, is strong. Total control, right? Understanding every byte? Sounds cool!
But hold on a sec. Before you embark on that epic quest, let's talk reality. Implementing ActivityPub correctly isn't just one task; it's like juggling several complex standards while riding a unicycle… blindfolded. It’s hard.
That's where Fedify comes in. It's a TypeScript framework designed to handle the gnarliest parts of ActivityPub development, letting you focus on what makes your app special, not reinventing the federation wheel.
This post will break down the common headaches of DIY ActivityPub implementation and show how Fedify acts as the super-powered pain reliever, starting with the very foundation of how data is represented.
At its core, ActivityPub relies on the ActivityStreams 2.0 vocabulary to describe actions and objects, and it uses JSON-LD as the syntax to encode this vocabulary. While powerful, this combination introduces significant complexity right from the start.
First, understanding and correctly using the vast ActivityStreams vocabulary itself is a hurdle. You need to model everything—posts (Note, Article), profiles (Person, Organization), actions (Create, Follow, Like, Announce)—using the precise terms and properties defined in the specification. Manual JSON construction is tedious and prone to errors.
Second, JSON-LD, the encoding layer, has specific rules that make direct JSON manipulation surprisingly tricky:
Note objects mean the same thing regarding the name property:// No name property
{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Note",
"content": "…"
}// Equivalent to:
{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Note",
"name": [],
"content": "…"
}content property here:// Single value
{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Note",
"content": "Hello"
}// Equivalent to:
{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Note",
"content": ["Hello"]
}Announce activities are semantically equivalent (assuming the URIs resolve correctly):{
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Announce",
// Embedded objects:
"actor": {
"type": "Person",
"id": "http://sally.example.org/",
"name": "Sally"
},
"object": {
"type": "Arrive",
"id": "https://sally.example.com/arrive",
/* ... */
}
}// Equivalent to:
{
"@context":
"https://www.w3.org/ns/activitystreams",
"type": "Announce",
// URI references:
"actor": "http://sally.example.org/",
"object": "https://sally.example.com/arrive"
}Attempting to manually handle all these vocabulary rules and JSON-LD variations consistently across your application inevitably leads to verbose, complex, and fragile code, ripe for subtle bugs that break federation.
Fedify tackles this entire data modeling challenge with its comprehensive, type-safe Activity Vocabulary API. It provides TypeScript classes for ActivityStreams types and common extensions, giving you autocompletion and compile-time safety. Crucially, these classes internally manage all the tricky JSON-LD nuances. Fedify's property accessors present a consistent interface—non-functional properties (like tags) always return arrays, functional properties (like content) always return single values or null. It handles object references versus embedded objects seamlessly through dereferencing accessors (like activity.getActor()) which automatically fetch remote objects via URI when needed—a feature known as property hydration. With Fedify, you work with a clean, predictable TypeScript API, letting the framework handle the messy details of AS vocabulary and JSON-LD encoding.
Once you can model data, you need to make your actors discoverable. This primarily involves the WebFinger protocol (RFC 7033). You'd need to build a server endpoint at /.well-known/webfinger capable of parsing resource queries (like acct: URIs), validating the requested domain against your server, and responding with a precisely formatted JSON Resource Descriptor (JRD). This JRD must include specific links, like a self link pointing to the actor's ActivityPub ID using the correct media type. Getting any part of this wrong can make your actors invisible.
Fedify simplifies this significantly. It automatically handles WebFinger requests based on the actor information you provide through its setActorDispatcher() method. Fedify generates the correct JRD response. If you need more advanced control, like mapping user-facing handles to internal identifiers, you can easily register mapHandle() or mapAlias() callbacks. You focus on defining your actors; Fedify handles making them discoverable.
// Example: Define how to find actors
federation.setActorDispatcher(
"/users/{username}",
async (ctx, username) => { /* ... */ }
);
// Now GET /.well-known/webfinger?resource=acct:username@your.domain just works!Serving actor profiles requires careful content negotiation. A request for an actor's ID needs JSON-LD for machine clients (Accept: application/activity+json) but HTML for browsers (Accept: text/html). Handling incoming activities at the inbox endpoint involves validating POST requests, verifying cryptographic signatures, parsing the payload, preventing duplicates (idempotency), and routing based on activity type. Implementing collections (outbox, followers, etc.) with correct pagination adds another layer.
Fedify streamlines all of this. Its core request handler (via Federation.fetch() or framework adapters like @fedify/express) manages content negotiation. You define actors with setActorDispatcher() and web pages with your framework (Hono, Express, SvelteKit, etc.)—Fedify routes appropriately. For the inbox, setInboxListeners() lets you define handlers per activity type (e.g., .on(Follow, ...)), while Fedify automatically handles validation, signature verification, parsing, and idempotency checks using its KV Store. Collection implementation is simplified via dispatchers (e.g., setFollowersDispatcher()); you provide logic to fetch a page of data, and Fedify constructs the correct Collection or CollectionPage with pagination.
// Define inbox handlers
federation.setInboxListeners("/inbox", "/users/{handle}/inbox")
.on(Follow, async (ctx, follow) => { /* Handle follow */ })
.on(Undo, async (ctx, undo) => { /* Handle undo */ });
// Define followers collection logic
federation.setFollowersDispatcher(
"/users/{handle}/followers",
async (ctx, handle, cursor) => { /* ... */ }
);Sending an activity requires more than a simple POST. Networks fail, servers go down. You need robust failure handling and retry logic (ideally with backoff). Processing incoming activities synchronously can block your server. Efficiently broadcasting to many followers (fan-out) requires background processing and using shared inboxes where possible.
Fedify addresses reliability and scalability using its MessageQueue abstraction. When configured (highly recommended), Context.sendActivity() enqueues delivery tasks. Background workers handle sending with automatic retries based on configurable policies (like outboxRetryPolicy). Fedify supports various queue backends (Deno KV, Redis, PostgreSQL, AMQP). For high-traffic fan-out, Fedify uses an optimized two-stage mechanism to distribute the load efficiently.
// Configure Fedify with a persistent queue (e.g., Deno KV)
const federation = createFederation({
queue: new DenoKvMessageQueue(/* ... */),
// ...
});
// Sending is now reliable and non-blocking
await ctx.sendActivity({ handle: "myUser" }, recipient, someActivity);Securing an ActivityPub server is critical. You need to implement HTTP Signatures (draft-cavage-http-signatures-12) for server-to-server authentication—a complex process. You might also need Linked Data Signatures (LDS) or Object Integrity Proofs (OIP) based on FEP-8b32 for data integrity and compatibility. Managing cryptographic keys securely is essential. Lastly, fetching remote resources risks Server-Side Request Forgery (SSRF) if not validated properly.
Fedify is designed with security in mind. It automatically handles the creation and verification of HTTP Signatures, LDS, and OIP, provided you supply keys via setKeyPairsDispatcher(). It includes key management utilities. Crucially, Fedify's default document loader includes built-in SSRF protection, blocking requests to private IPs unless explicitly allowed.
The fediverse is diverse. Different servers have quirks. Ensuring compatibility requires testing and adaptation. Standards evolve with new Federation Enhancement Proposals (FEPs). You also need protocols like NodeInfo to advertise server capabilities.
Fedify aims for broad interoperability and is actively maintained. It includes features like ActivityTransformers to smooth over implementation differences. NodeInfo support is built-in via setNodeInfoDispatcher().
Beyond the protocol, building any server involves setup, testing, and debugging. With federation, debugging becomes harder—was the message malformed? Was the signature wrong? Is the remote server down? Is it a compatibility quirk? Good tooling is essential.
Fedify enhances the developer experience significantly. Being built with TypeScript, it offers excellent type safety and editor auto-completion. The fedify CLI is a powerful companion designed to streamline common development tasks.
You can quickly scaffold a new project tailored to your chosen runtime and web framework using fedify init.
For debugging interactions and verifying data, fedify lookup is invaluable. It lets you inspect how any remote actor or object appears from the outside by performing WebFinger discovery and fetching the object's data. Fedify then displays the parsed object structure and properties directly in your terminal. For example, running:
$ fedify lookup @fedify-example@fedify-blog.deno.devWill first show progress messages and then output the structured representation of the actor, similar to this:
// Output of fedify lookup command (shows parsed object structure)
Person {
id: URL "https://fedify-blog.deno.dev/users/fedify-example",
name: "Fedify Example Blog",
published: 2024-03-03T13:18:11.857Z, // Simplified timestamp
summary: "This blog is powered by Fedify, a fediverse server framework.",
url: URL "https://fedify-blog.deno.dev/",
preferredUsername: "fedify-example",
publicKey: CryptographicKey {
id: URL "https://fedify-blog.deno.dev/users/fedify-example#main-key",
owner: URL "https://fedify-blog.deno.dev/users/fedify-example",
publicKey: CryptoKey { /* ... CryptoKey details ... */ }
},
// ... other properties like inbox, outbox, followers, endpoints ...
}This allows you to easily check how data is structured or troubleshoot why an interaction might be failing by seeing the actual properties Fedify parsed.
Testing outgoing activities from your application during development is made much easier with fedify inbox. Running the command starts a temporary local server that acts as a publicly accessible inbox, displaying key information about the temporary actor it creates for receiving messages:
$ fedify inbox
✔ The ephemeral ActivityPub server is up and running: https://<unique_id>.lhr.life/
✔ Sent follow request to @<some_test_account>@activitypub.academy.
╭───────────────┬─────────────────────────────────────────╮
│ Actor handle: │ i@<unique_id>.lhr.life │
├───────────────┼─────────────────────────────────────────┤
│ Actor URI: │ https://<unique_id>.lhr.life/i │
├───────────────┼─────────────────────────────────────────┤
│ Actor inbox: │ https://<unique_id>.lhr.life/i/inbox │
├───────────────┼─────────────────────────────────────────┤
│ Shared inbox: │ https://<unique_id>.lhr.life/inbox │
╰───────────────┴─────────────────────────────────────────╯
Web interface available at: http://localhost:8000/You then configure your developing application to send an activity to the Actor inbox or Shared inbox URI provided. When an activity arrives, fedify inbox only prints a summary table to your console indicating that a request was received:
╭────────────────┬─────────────────────────────────────╮
│ Request #: │ 2 │
├────────────────┼─────────────────────────────────────┤
│ Activity type: │ Follow │
├────────────────┼─────────────────────────────────────┤
│ HTTP request: │ POST /i/inbox │
├────────────────┼─────────────────────────────────────┤
│ HTTP response: │ 202 │
├────────────────┼─────────────────────────────────────┤
│ Details │ https://<unique_id>.lhr.life/r/2 │
╰────────────────┴─────────────────────────────────────╯
Crucially, the detailed information about the received request—including the full headers (like Signature), the request body (the Activity JSON), and the signature verification status—is only available in the web interface provided by fedify inbox. This web UI allows you to thoroughly inspect incoming activities during development.
When you need to test interactions with the live fediverse from your local machine beyond just sending, fedify tunnel can securely expose your entire local development server temporarily. This suite of tools significantly eases the process of building and debugging federated applications.
Implementing the ActivityPub suite of protocols from scratch is an incredibly complex and time-consuming undertaking. It involves deep dives into multiple technical specifications, cryptographic signing, security hardening, and navigating the nuances of a diverse ecosystem. While educational, it dramatically slows down the process of building the actual, unique features of your federated application.
Fedify offers a well-architected, secure, and type-safe foundation, handling the intricacies of federation for you—data modeling, discovery, core mechanics, delivery, security, and interoperability. It lets you focus on your application's unique value and user experience. Stop wrestling with low-level protocol details and start building your vision for the fediverse faster and more reliably. Give Fedify a try!
Getting started is straightforward. First, install the Fedify CLI using your preferred method. Once installed, create a new project template by running fedify init your-project-name.
Check out the Fedify tutorials and Fedify manual to learn more. Happy federating!