The state of Firebase alternatives in 2020?

There really isn’t a competitor. Supabase is trying to combine OSS tooling into a somewhat similar offering but it’s not nearly as feature rich as Firebase. That having been said, most people use Firebase for real time DB and auth, and Supabase supports that now. It doesn’t, however, support offline use cases, or any of the advanced functionality of firebase.

Pouch and couch solve the offline data scenario and live replication, but no auth story and the mapping of users to data is problematic (unless you build a proxy layer, there’s not an easy way to have some data be public, some private, and some shared).

Realm is paid these days, I believe, and it solves the data replication, but again, no auth.

Is open source Parse still going?

https://parseplatform.org/

https://couchdb.apache.org/ + https://pouchdb.com/

I'm hedging my bets by using Datalog and the Datomic protocol wherever I can: https://tonsky.me/blog/datomic-as-protocol/

And keeping a close eye on Differential Dataflow: https://github.com/TimelyDataflow/differential-dataflow/

DD is commercialized in Materialize: https://materialize.io/

The solution is likely to arrive in the Clojure/ClojureScript ecosystem before it arrives anywhere else because tools like Datascript lend itself to this type of thinking, e.g. 3DF: https://github.com/sixthnormal/clj-3df/

The closest thing we have to streaming updates right now is FactUI, which uses the Clara rules engine, but it's IMO hampered by limitations of Clara and Cljs namespacing: https://github.com/arachne-framework/factui

The RETE algorithm is a less general solution to incremental updates. Zach Oakes is doing some interesting work with O'Doyle Rules: https://github.com/oakes/odoyle-rules

Firebase is an ecosystem of products. Which parts of firebase are your priority and what do you want to get done?

https://supabase.io/

Plug: I wrote a small clojurescript wrapper around firebase. You can try it out here. -> https://firemore.org/

I haven't found another solution that can get you started as quickly as Firebase can. Most common complaint I hear from developers about Firebase is the concern that Google will drop support at some point. I can't fault that concern, but Google seems to drop developer products at a much lower rate than customer products.

Maybe not exactly what you're looking for but:

https://www.gun.eco/

Biff is open source but "alpha quality software"

https://github.com/jacobobryant/biff

For the database and auth check FaunaDB.

It doesn't have sync or realtime yet, but it's a much better database overall.

PouchDB is amazing. You can use their server side components and scale into couchdb later.

Good 'ol AWS lambda might be an option (+other PaaS services as needed).

hasura.io

How about MongoDB Atlas?

apollo, AWS Cognito, and AWS Appsync