Are there key:value databases that connect via a file rather than a network?

Question

Database

I'm looking for a key - value database with a connection through a file, not a network.
You need something like MongoDB, but connected like SQLite, through a file, to carry along with the program. At the same time, the base must support multithreading (the program itself is multithreaded)
. Something more or less mainstream and documented is desirable.

Answer 1

However, this is one of many, in my opinion Berkeley is too heavy
https://ru.wikipedia.org/wiki/Berkeley_DB

Answer 2

https://github.com/google/leveldb

Answer 3

RocksDB
LevelDB
WiredTiger