There are 3 repositories under activitystreams topic.
Federated blogging application, thanks to ActivityPub (now on https://git.joinplu.me/ — this is just a mirror)
Golang fediverse server.
Powering connected social communities with open software.
Activity Streams 2.0
ActivityPub for WordPress
A PHP implementation of ActivityPub protocol based upon the ActivityStreams 2.0 data format.
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
unofficial Activity Streams 2.0 vocabulary data and alternative docs
Command-line tools for interacting with the pump.io API
Specifications to implement intent feature for ActivityPub
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