PostgREST: REST API for any Postgres database
Big thumbs up for PostgREST.  While it hasn't been completely issue free for me, it's a great project making a ton of progress and the community is very helpful and responsive.I found myself butting heads with the limitations of the API quite a bit, but since it has a wonderful RPC feature, you can always drop a custom endpoint to do what you need to do without completely ejecting.You can also surface other systems with PostgREST, using foreign data wrappers.  This is great because you can use Postgres's rock solid role system to manage access to them.  FDWs are surprisingly easy to write using Multicorn, and you can get pretty crazy with them if you're fronting a read replica (which you should be doing anyway once past the proof of concept stage).