There are 3 repositories under activitystreams topic.
Social server with an ActivityStreams API
Federated blogging application, thanks to ActivityPub (now on https://git.joinplu.me/ — this is just a mirror)
Golang fediverse server.
ActivityStreams & ActivityPub in golang, oh my!
Powering connected social communities with open software.
Multiple accounts client for multiple Social networks. For Android
Activity Streams 2.0
Self-hosted Soundtracks and Podcasts sharing, with ActivityPub federation.
ActivityPub for WordPress
A PHP implementation of ActivityPub protocol based upon the ActivityStreams 2.0 data format.
Golang ActivityPub Server Framework
Flask-based ActivityPub server
Activity Feed, Timeline, News Feed, Notification Feed with MongoDB, Node and CRDTs
An OStatus library written in Go
An ActivityPub server that reblogs all the statuses of certain actors.
An inofficial proposal for ActivityPub - JSON Schemas (draft 07)
Hanatachi is a free, open-source social network server for federated blogging
Activity Streams is a simple specification used to describe social actions around the web.
Presentations on: golang and ActivityPub
Model classes based on open data specifications
unofficial Activity Streams 2.0 vocabulary data and alternative docs
Command-line tools for interacting with the pump.io API
Social Media Platform for City Life.
Specifications to implement intent feature for ActivityPub
ActivityPub Address Registry - A de-centralized registrar for servers implementing the ActivityPub Specification.
Activity Streams validation for Typescript
DogPark (Distributed "Open Graph Protocol" Accessors Registry Kingdom) is a federation network for providing a secure way to get OGP metadata.
A program for importing Mastodon user data takeouts into Perkeep
THIS REPO HAS MOVED TO https://github.com/sockethub/sockethub/ - parses the IRC protocol into ActivtyStreams objects