For the record, for a lot of time Firefox Sync used to be exactly like that. https://blog.mozilla.org/services/2011/03/22/get-syncing-with-firefox-4/ https://b

For the record, for a lot of time Firefox Sync used to be exactly like that. https://blog.mozilla.org/services/2011/03/22/get-syncing-with-firefox-4/ https://blog.mozilla.org/services/2011/03/22/get-syncing-wit... Not only one of the first questions would be whether you want to use a Custom Sync Server, but this "Custom Sync Server" could be something as trivial as WebDAV server (if you have any kind of public-facing HTTP server, it almost certainly already supports this, or does so with minimal extra dependencies) . Then it would also ask you for the E2EE key, separately from the login key.