Atproto is a federated protocol for large social applications whose founding promise is that you can leave with your account; data lives on host servers, every host feeds one shared public stream, and it is not a blockchain.

It frames the whole series: the design choices follow from portability and a global view.

The Authenticated Transfer Protocol, atproto, is a protocol for large social applications. Its founding promise: your account and its data are a bag you can carry to another server.

It is federated. Your data lives on a host server, not on your phone. It is not a blockchain, and does not use one.

But it is not a web of small islands either. Every host feeds one big shared stream, and apps build their views from it.

Everything in that stream is public. Posts, likes, follows: signed, and readable by any app.

This series takes it apart one idea at a time. Identity. Repositories. Sync. And the apps on top.

Check yourself. Where does your data live, and who can read the shared stream?