AT Protocol is a federated networking protocol built around typed records, content addressing, and the separation of data from applications. Those are also the design principles behind Underlay. The overlap is not superficial. The two systems solve different problems in complementary ways, and connecting them is straightforward.
Underlay
Publish structured data as versioned, permanent collections with schemas, provenance, and content addressing built in. Whether you're a research lab, a newsroom, a community archive, or a single developer, Underlay makes the knowledge you hold discoverable, verifiable, and easy to build on.
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.
AT Protocol - AT Protocol
Specification for the Authenticated Transfer Protocol (AT Protocol)
Federation Architecture | Bluesky
The AT Protocol is made up of a bunch of pieces that stack together. Federation means that anyone can run the parts that make up the AT Protocol themselves, such as their own server.
Glossary of terms - AT Protocol
A collection of terminology used in the AT Protocol and their definitions.
Streaming Data - AT Protocol Docs - AT Protocol
Synchronizing and streaming data from the AT Protocol.
AT Protocol Primer
What is the AT Protocol and why does it matter in the grand scheme of the web
Self-hosting - AT Protocol Docs - AT Protocol
Self-hosting components of the AT Protocol Stack.
blogged: Building on AT Protocol dbushell.com/2026/03/10/building-on-at-pro…
Building on AT Protocol
dbushell.comI wrote up my talk at @localfirstconf.com as a blogpost The AT Protocol is a high-scale network by design. It works by codifying proven architectures into a protocol. If you've ever used kafka to connect some backend services, then you basically know how atproto works.
Starting from scale in the design of the AT Protocol
pfrazee.leaflet.pub
