Firefox supports custom Sync (and FxA) servers. This bug is only for exposing that configuration in more polished UI. Here's how to run your own Sync server: https://docs.services.mozilla.com/howtos/run-sync-1.5.html Here's how to run your own Firefox Accounts server (much harder): https://docs.services.mozilla.com/howtos/run-fxa.html#howto-run-fxa Both of those guides include documentation for how to configure desktop Firefox. If you're only self-hosting storage, you just need to set identity.sync.tokenserver.uri. If you're self-hosting FxA+token+Sync, you can use the autoconfig URL. See those docs for more details.