So the alternative options are:
- pouchDB - https://github.com/pouchdb/pouchdb
- RxDB - https://github.com/pubkey/rxdb
- gunDB - https://github.com/amark/gun
- horzion - https://github.com/rethinkdb/horizon
- firebase - https://firebase.google.com/
- pouchDB - https://github.com/pouchdb/pouchdb
- RxDB - https://github.com/pubkey/rxdb
- gunDB - https://github.com/amark/gun
- horzion - https://github.com/rethinkdb/horizon
- firebase - https://firebase.google.com/
I just wanted to have a next-to-complete list.
Couchbase fits the bill as well, and has serious real-world deployments. https://developer.couchbase.com/mobile (Yes, I work for them.)