ferretdb is a MongoDB open source alternative based on PostgreSQL
published on 2023/04/13
The core of our solution is a stateless proxy, which converts MongoDB protocol queries to SQL, and uses PostgreSQL as a database engine. This will be compatible with MongoDB drivers, and should work as a drop-in replacement to MongoDB in many cases.
It doesn't have feature parity with MongoDB but it might be good enough for a lot of projects that relied on MongoDB.