Databases

Postgres - Widely used, open source database with good data integrity and feature set. The typical recommendation for bots.

MySql - The de facto SQL standard in software development. Usually not recommended here due to the decreased feature set in comparison to PostgreSQL, but strongly time-tested.

SqLite - File-based DB, no authentication. Lack of networking means query-by-query time is relatively fast, but tends to chug past a certain amount of load.

MongoDB - Cloud based database