Authenticated Transfer (AT) is a collection of protocol components that together provide a generic framework for interoperable social web applications, using global aggregations of interlinked, self-certifying data records. This informational document provides an overview of the entire system, as implemented in late 2025. Some of those components may be in scope as work for the IETF, while other components may not. Many components are general-purpose and may find use outside of the context of AT. The intent of this document is to provide context for how all the components can fit together for certain use cases.
AT Protocol - AT Protocol
Specification for the Authenticated Transfer Protocol (AT Protocol)
AT Protocol
The AT Protocol is a protocol and set of open standards for decentralized publishing and distribution of self-authenticating data within the social web. It serves as the technical foundation of the Bluesky social network, originally developed as a reference implementation for the protocol, as well as an ecosystem of interoperable social applications and services collectively referred to as the ATmosphere.
The AT Protocol | Bluesky
The AT Protocol (Authenticated Transfer Protocol, or atproto) is a standard for public conversation and an open-source framework for building social apps.
OAuth Patterns - AT Protocol Docs - AT Protocol
Auth for AT Protocol application developers.
OAuth Patterns - AT Protocol Docs - AT Protocol
Auth for AT Protocol application developers.
OAuth for AT Protocol | Bluesky
We are very happy to release the initial specification of OAuth for AT Protocol! This is expected to be the primary authentication and authorization system between atproto client apps and PDS instances going forward, replacing the current flow using App Passwords and createSession over time.
Drafts, private data, and obscurity.
The at:// protocol currently lacks any real means to have data which is both 'on-protocol', i.e. stored on your PDS in a way that you can guarantee access to...
Drafts, private data, and obscurity.
The at:// protocol currently lacks any real means to have data which is both 'on-protocol', i.e. stored on your PDS in a way that you can guarantee access to...
AT Protocol Roadmap (Spring 2026) - AT Protocol
Updates to the AT Protocol roadmap, including Permissioned Data and Account Experience.
AT Protocol Roadmap (Spring 2026) - AT Protocol
Updates to the AT Protocol roadmap, including Permissioned Data and Account Experience.
chrisvanderloo.com/at-astro
An Astro integration for the AT Protocol. Implements authentication and content loaders for ATProto records.