It's worth noting that Firebase doesn't have a true offline-first architecture, but rather cloud-first: By default, queries run against the cloud and results of

It's worth noting that Firebase doesn't have a true offline-first architecture, but rather cloud-first: By default, queries run against the cloud and results of those specific queries are temporarily cached on the client. By default Firestore will try to reach the server first before falling back to the local cache, which can result in a subpar UX on a patch network connection. It does also provide store-and-forward of updates from client to server. But it's not a true offline-first architecture since it does not preemptively sync a database to the local user device for offline-by-default access. Regarding Postgres, that is where tools like PowerSync (disclosure: co-founder) and ElectricSQL are useful, which are both sync layers for Postgres for offline-first architecture.