# ActivityPub: a federated protocol with formal change rules

Canonical source : [ActivityPub: a federated protocol with formal change rules](<https://sebastien.rigaux.be/en/tech-watch/links/activitypub-a-federated-protocol-with-formal-change-rules>)

The W3C repository presents ActivityPub, a decentralized social networking protocol that combines a client-to-server API with a federated server-to-server API. Built on the ActivityStreams 2.0 JSON-LD format, it supports extensible activity descriptions and different kinds of social applications.

The repository also explains how to evolve a published recommendation: clarifications belong in the Primer, corrections follow an errata process, and breaking changes require a new working group. That formal governance reflects the deployment cost of changing a protocol used by many independently operated servers.

- Selected on : 2026-10-29

- Entry updated : 2026-11-07T20:32:37+0000

- Format : Article

- Source language : EN

Original resource : [ActivityPub: a federated protocol with formal change rules](<https://github.com/w3c/activitypub>)

Tags : ActivityPub · JSON-LD · [API Design](<https://sebastien.rigaux.be/en/tech-watch/tags/api-design>)

Available versions : [Français](<https://sebastien.rigaux.be/veille/liens/activitypub-le-protocole-federe-et-ses-regles-devolution>) · [English](<https://sebastien.rigaux.be/en/tech-watch/links/activitypub-a-federated-protocol-with-formal-change-rules>)

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