Ask HN: What are some small OSSs with clean and maintainable codebase?

Disclaimer: This has been asked multiple times, but unfortunately, the examples are always same few very large ones(BSD, Linux Kernel, glibc, gnome, ReactJS etc.) which are daunting to me.

What I am looking for are examples of some very small projects that are: 1. very well written/adhere to clean code principles 2. good documentation (preferred) 3. small enough to read up in few hours (important) 4. hosted in accessible services(e.g. github/gitlab/bitbucket etc.) (important) 5. has non-arcane build/compile instructions/requirements

Also, small hobby projects that fulfill some/all points(1-5) are welcome.

It will be appreciated if you explain, why you think that particular example fulfills some/all required points(1-5) when you mention one. (Bonus)

P.S. I am aware of "first timers only/good for beginners" lists, so please don't post about these.