[atombender]

If you like Firebase, I'd like to give a shout-out to Sanity [1]. (Disclosure: I work part-time on the backend, but I'm not an employee and I don't work on the product itself; but call this a shameless plug if you will!)

Sanity is a headless CMS, but the API itself is like a souped-up Firebase and can be used on its own without adopting the Sanity UI. It's got many of the same features -- web API, change watching via WebSockets -- but adds support for joins, fine-grained patches (CRDT-like but not actually), transaction history APIs, fine-grained document-level permissions, and many other neat things. We are particularly proud of the query language, GROQ [2], which is a very powerful superset of JSON that allows you to express transformation pipelines over structured data.

Sanity is hosted on Google Cloud, too, so performance when used inside GCP should be great.

[1] https://sanity.io

[2] https://www.sanity.io/docs/data-store/how-queries-work

[fasteo]

Thanks for the pointer to sanity. After a quick read over the docs, it seems a really impressive piece of software.