This looks like an excellent read for anyone looking to level up their fullstack JS chops:

I do React consulting and this is a showcase product I’ve built in my spare time. It’s a very good example of modern, real-world React codebase.

There are many showcase/example React projects out there but most of them are way too simple. I like to think that this codebase contains enough complexity to offer valuable insights to React developers of all skill levels while still being relatively easy to understand.