There are 6 repositories under activitystreams topic.
Fast, fun, small ActivityPub server. READ ONLY MIRROR! Now on Codeberg instead: https://codeberg.org/superseriousbusiness/gotosocial
Federated blogging application, thanks to ActivityPub (now on https://git.joinplu.me/ — this is just a mirror)
:bulb: dokieli is a clientside editor for decentralised article publishing, annotations and social interactions
ActivityPub for WordPress
Powering connected social communities with open software.
Activity Streams 2.0
A PHP implementation of ActivityPub protocol based upon the ActivityStreams 2.0 data format.
Flask-based ActivityPub server
An attempt to build a spec-compliant ActivityPub core library.
Activity Feed, Timeline, News Feed, Notification Feed with MongoDB, Node and CRDTs
Modular implementation of ActivityPub in C#
An ActivityPub server that reblogs all the statuses of certain actors.
An OStatus library written in Go
An inofficial proposal for ActivityPub - JSON Schemas (draft 07)
Hanatachi is a free, open-source social network server for federated blogging
A .NET implementation of the Activity Streams vocabulary in the form of classes that can be serialized/deserialized using System.Text.Json
ActivityPub JS/TS models
Activity Streams is a simple specification used to describe social actions around the web.
alternative docs for ActivityStreams 2.0 vocabulary
Activity Streams validation for Typescript
Presentations on: golang and ActivityPub
awesome (work in progress) federated social networking software
Simple, post-only ActivityPub implementation in PHP
Command-line tools for interacting with the pump.io API
ActivityPub / ActivityStream basic serialization/deserialization for Ruby
Index of open-source ActivityPub projects using C# or .NET
Modeling non-verbal communication as an ActivityStreams extension