There Are No Instances in ATProto
ATProto, the protocol behind Bluesky, does not have "instances" like Mastodon or email servers; instead, it uses a Personal Data Server (PDS) architecture where users own their data and can switch providers transparently.
Background
- ATProto is the open protocol that powers Bluesky, a decentralized social network that emerged as an alternative to Twitter/X.
- The post critiques a common misunderstanding: people treat ATProto like Mastodon (ActivityPub), where each server is a self-contained "instance." In ATProto, accounts, data, and moderation operate across a more fluid architecture of Personal Data Servers (PDS), relays, and app views.
- Dan Abramov, the author, is a well-known React core team member and engineer; here he writes from the perspective of a user exploring ATProto's design, not as an official spec author.
- The key distinction: in Mastodon, switching instances means moving to a different community with a different URL and timeline. In ATProto, you can move your account between PDSes without changing your handle or losing your social graph—there are no walled-off "instances" in the Mastodon sense.