I switched from SSDB to Kvrocks recently, because SSDB is abandoned and the author missing for 3 years now. I used to recommend SSDB, but now there's better alternatives available:

https://github.com/apache/kvrocks

https://github.com/sabledb-io/sabledb

These are great recommendations, thanks!

Its also worth checking out kvrocks, which is a redis interface on top of rockdb that's part of the Apache project, and very well maintained.

And which is not in-memory at all.

It can cache in-memory using RocksDBs caching mechanisms.