Codewars launched in 2012 with a martial arts-inspired approach to coding practice. On the platform, coding challenges are called “kata” and difficulty levels are ranked using the kyu/dan system borrowed from martial arts — 8 kyu is the easiest, 1 kyu is the hardest, and dan ranks are for those who’ve mastered the fundamentals. It’s a clever framing that makes practice feel like training.
What makes Codewars special is that its challenges are almost entirely community-created. Users write and publish their own kata, which go through a review process before becoming available to everyone. This has produced an enormous library of over 10,000 challenges covering algorithms, logic, math, string manipulation, and language-specific features across 55+ programming languages.
After solving a kata, learners can view solutions from other users — and this is where much of the real learning happens. Seeing how experienced developers approach the same problem often reveals more elegant or idiomatic solutions. The community votes on the best solutions, creating a curated collection of high-quality code examples.
Codewars is free to use and supported by its community. The honor and rank system provides motivation, and many developers use it alongside other platforms to sharpen their problem-solving skills. It’s particularly popular among developers who enjoy the puzzle-solving aspect of programming and want to explore multiple languages. The platform has attracted over 3 million registered users worldwide.
