Ask HN: What are your most recommended GitHub repos to learn from?

My background is mostly frontend development and I'm always looking to learn more about C.S. fundamentals and how JS libraries can be practically used for app development. I find myself checking out the following from time to time:

https://github.com/gothinkster/realworld

https://github.com/prakhar1989/awesome-courses/blob/master/README.md

https://github.com/jwasham/coding-interview-university

Any good gems out there you recommend?