Hacker News Reader

It's still open source and actively maintained by Apple, they use it internally.

It is now. There were a few years where it had basically disappeared (2015-2018). When Apple eventually put it back in the open-source world, it was done with little fanfare so it could be easy to miss.

> put it back in the open-source world

Just to clarify - FoundationDB was never open source before 2018. Binaries were available under certain conditions, but no source.

Deno KV uses FoundationDB, for example:

https://deno.com/blog/building-deno-kv

same guy who wrote mvsqlite btw

It re-appeared after 10 or so years though.

Really, what is the reason why?

Apple thought it would be in their best interest to release it.

Apple acquired the company in 2015 and 3 years later open-sourced the database.

(so much misinformation in this thread, this isn't hard to check)