Developed by Bluesky

The AT Protocol is a networking technology created to power the next generation of social applications. The initial reference application,,provides a global-scale microblogging experience.

Protocol Overview

The Authenticated Transfer Protocol, aka atproto, is a federated protocol for large-scale distributed social applications. This document will introduce you to the ideas behind the AT Protocol.

From the Protocol Overview


The Authenticated Transfer Protocol (AT Protocol or atproto) is a generic federated protocol for building open social media applications. Some recurring themes and features are:

  • self-authenticating data and identity, allowing seamless account migrations and redistribution of content
  • design for "big world" use cases, scaling to billions of accounts
  • delegated authority over application-layer schemas and aggregation infrastructure
  • re-use of existing data models from the dweb protocol family and network primitives from the web platform

From the Specification


Personal Data Server. Similar in concept to Personal Data Store, except this is the software server and can host multiple user accounts.

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