Fedify: an ActivityPub server framework
If you're considering creating your own implementation of #ActivityPub, consider #Fedify.
Implementing ActivityPub from scratch requires more than you might think. WebFinger, HTTP Signatures, Linked Data Signatures, Object Integrity Proofs, NodeInfo, queues for sending and receiving activities, followers collection synchronization, remote object lookups, interoperability with Mastodon, Akkoma, Misskey, Threads, and more…
Just use Fedify and feel free to create your own ActivityPub implementation!