I'm a recent convert to sqlite - started using it in CLI Go apps as a more robust way of handling large data sets than building my own bespoke in memory databases. It's not often I come across software that impresses and amazes me as much as sqlite does. It's tiny, ridiculously easy to implement, writes 1 flat file, uses comparatively little memory, and is /fast/. I don't even know how they managed to make it so fast given all the other constraints.

Seriously impressive database.