Specs and RFCs used

OStatus
Suite of federation protocols
- Salmon
  Delivery of targeted events to users
- Portable Contacts
  Encoding profile information in Atom
- Atom
  Representing user feeds
- Atom ActivityStreams
  Encoding rich social post metadata
- Atom Threading
  Encoding chains of conversations
- WebSub (formerly PubSubHubbub)
  Broadcasting of real-time updates to followers
WebFinger
User-on-domain lookups
HTTP Signatures
Server-to-server authentication of requests
ActivityPub
Federation protocol