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Bluesky and the AT Protocol: Usable Decentralized Social Media

Martin Kleppmann, Paul Frazee, Jake Gold, Jay Graber, Daniel Holmgren, Devin Ivy, Jeromy Johnson, Bryan Newbold, Jaz Volpert

TL;DR

The architecture of Bluesky and the AT Protocol is introduced, and it is explained how the technical design of Bluesky is informed by its goals: to enable decentralization by having multiple interoperable providers for every part of the system.

Abstract

Bluesky is a new social network built upon the AT Protocol, a decentralized foundation for public social media. It was launched in private beta in February 2023, and has grown to over 10 million registered users by October 2024. In this paper we introduce the architecture of Bluesky and the AT Protocol, and explain how the technical design of Bluesky is informed by our goals: to enable decentralization by having multiple interoperable providers for every part of the system; to make it easy for users to switch providers; to give users agency over the content they see; and to provide a simple user experience that does not burden users with complexity arising from the system's decentralized nature. The system's openness allows anybody to contribute to content moderation and community management, and we invite the research community to use Bluesky as a dataset and testing ground for new approaches in social media moderation.

Bluesky and the AT Protocol: Usable Decentralized Social Media

TL;DR

The architecture of Bluesky and the AT Protocol is introduced, and it is explained how the technical design of Bluesky is informed by its goals: to enable decentralization by having multiple interoperable providers for every part of the system.

Abstract

Bluesky is a new social network built upon the AT Protocol, a decentralized foundation for public social media. It was launched in private beta in February 2023, and has grown to over 10 million registered users by October 2024. In this paper we introduce the architecture of Bluesky and the AT Protocol, and explain how the technical design of Bluesky is informed by our goals: to enable decentralization by having multiple interoperable providers for every part of the system; to make it easy for users to switch providers; to give users agency over the content they see; and to provide a simple user experience that does not burden users with complexity arising from the system's decentralized nature. The system's openness allows anybody to contribute to content moderation and community management, and we invite the research community to use Bluesky as a dataset and testing ground for new approaches in social media moderation.
Paper Structure (22 sections, 2 figures)

This paper contains 22 sections, 2 figures.

Table of Contents

  1. Introduction
  2. The Bluesky Social App
  3. Moderation Features
  4. User Handles
  5. Custom Feeds and Algorithmic Choice
  6. The AT Protocol Architecture
  7. User Data Repositories
  8. Personal Data Servers (PDS)
  9. Indexing Infrastructure
  10. The Relay
  11. The App View
  12. Labelers and Feed Generators
  13. User Identity
  14. Resolving DID documents
  15. The did:plc DID method
  16. ...and 7 more sections

Figures (2)

  • Figure 1: The main services involved in providing Bluesky, and data flows between them. Icons from Flaticon.com.
  • Figure 2: A handle resolves to a DID, and a DID resolves to a DID document, which in turn references the handle, DID, and the user's public key. Icons from Flaticon.com.