I’ve always loved SQLite but now I love it more. Maintained by three people. 600 lines of test code for every line of code. Design decisions favor robustness over feature richness at every return. However widely you think it’s used, your guess is way low.
A striking example of the weird and wonderful things that can be built when shareholder value is not the primary goal.
https://fosstodon.org/@amoroso/113758608409377815