We know for a fact that this is a repo on GitHub that exists. But it's not open.
Why is it closed source? Do I really have to reverse engineer the API from the clients (Android, iOS, and the Mastodon server) myself and build a compatible alternative?
The Mastodon server uses it as an update check, and so do the apps IIRC. And the apps use it to see the "catalog of instances".
re: Mastodon has closed source components@moshidon@graphite@nimona@megalodon Absolutely, yes. And also why emoji reactions are a thing (though to be fair, Akkoma is another reason)