ActivityPubCopy wiki link

ActivityPub is a W3C Recommendation for decentralized social networking. It defines a client-to-server API for creating and managing content and a server-to-server API for federated delivery.

Trust modelCopy wiki link

Accounts and public identities are normally hosted by an instance. The instance authenticates its users, stores their objects, delivers activities, and applies local moderation and federation policy. Remote instances make their own policy decisions.

Audience fields support public, addressed, and hidden-recipient delivery. They are access-control instructions to servers, not general end-to-end encryption. Origin and recipient servers can process restricted content, and remote copies weaken authoritative deletion.

Best fitCopy wiki link

ActivityPub is strongest as a common publishing language for communities with plural hosting and moderation. Its common user@domain identity remains tied to a host; implementation migration features do not provide the same unchanged cryptographic identity as AT Protocol or Nostr.

Secure and decentralized communication stacks separates this social-publishing role from confidential messaging.