Postgres and SQLite are free.
Open-source relational database. The usual pick when you want real SQL.
Try itReliable relational database
JSON without leaving SQL
Free to run yourself
You manage backups and upgrades
Heavier than SQLite for a tiny app
A SQL database stored in one file, with no server to run.
Try itNothing to install beyond the library
Easy to copy, back up, or reset in development
Drizzle can use it the same way as Postgres
One writer at a time is the comfortable limit
You outgrow it once you need hosted auth and storage