GitHub
GitHub is where over 100 million developers shape the future of software, together. Contribute to the open source community, manage your Git repositories, review code like a pro, track bugs and fea...
Codewars
A coding practice website for all programming levels – Join a community of over 3 million developers and improve your coding skills in over 55 programming languages!
Advent of Code
Advent of Code is an Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.