AT Protocol

The AT Protocol (Authenticated Transfer Protocol) is an open, decentralized protocol for social networking, developed by Bluesky as a project that began inside Twitter. It is built so that people own portable identities and data that move between services, rather than being locked into a single platform. A federated network of interoperable servers — similar in spirit to email — carries the traffic, and users can choose or customize the algorithms that curate what they see.

• Portable identity - Users hold decentralized identifiers they can carry from one provider to another without losing their connections.
• Federation - Independent servers interconnect into one network, so no single operator controls the whole graph.
• Data ownership - People retain their content and can move it, reducing lock-in and platform-level censorship.
• Algorithmic choice - Feed generation is open and swappable, giving users transparency and control over what surfaces.

For API builders, the AT Protocol is one of the more interesting live experiments in decentralized, standards-based social infrastructure — an open surface anyone can build clients, feed generators, and services against rather than a walled proprietary API. Its data-ownership and portable-identity model matters as agents increasingly act on behalf of users across platforms, since it makes identity and content something the user carries rather than something a single provider gates. It sits alongside older syndication standards like Atom in the long lineage of attempts to keep the social web open.