Comment by kisamoto

It can be the backend itself if you just need auth (both authentication and authorization) and your SQL tables to be a REST API. This often suits frontend single page applications in JS/TS and Pocketbase also provides a JS SDK to ease this (with realtime updates). It's a similar model to Firebase but without the lock-in.

However if you want to write more logic you can also import Pocketbase as a library and extend it with hooks, custom endpoints etc. all written in Go.

Edit: Added more info about using Pocketbase with a JS SPA frontend.