Ask HN: Any other databases on single disk file like SQLite exist?

Berkeley DB and variants:

https://en.wikipedia.org/wiki/Berkeley_DB

There's duckdb which seems very similar. I haven't actually used it for anything yet so YMMV.

Firebird, maybe:

https://firebirdsql.org/manual/fbint-structure.html

Firebird can be used either with or without a server. It's also possible to switch from one to the other while keeping the exact same database file.

Apache H2, and Apache Derby. There's quite a few that are available if you only need them to be supported on the JVM.

https://ejdb.org/

standalone nosql

What are your requirements (data model, non-functional priorities, data size, data types)?

Nothing super particular at this time, but generally: In the past I've wanted to spin up something like ElasticSearch in a desktop or mobile app. I really love the SQLite model of a simple file. This type of just dealing with a file has grown in popularity recently. See [rqlite](https://github.com/rqlite/rqlite) and [HN:Consider SQLite](https://news.ycombinator.com/item?id=29727707)