Explore and get fluent in 57 programming languages

Over 3,450 coding exercises. From "Allergies" to "Zebra Puzzle".

Learn by doing. Get better at programming through fun coding exercises that build your understanding of concepts.

Deepen your knowledge with human mentoring, for free.

Discover new and exciting ways to approach an exercise by getting mentored on it. Become more familiar with the conventions, idioms and opinions of a particular programming language.

You don’t know what you don’t know

When learning a new language, the hardest part is not being aware of the gaps in your knowledge. Our mentors can look at your code and immediately see the ideas you're not familiar with and give you a level-up by unlocking new knowledge.

Becoming fluent in a language is more than being able to write code in it - it's about being able to think in that language. Our mentors will help guide you to how to reshape your thinking to write idiomatic code.

Getting feedback from real people is an amazingly exciting way to learn. And becoming a mentor and giving feedback yourself is an even bigger step forward. So complete the circle - be mentored and mentor 🎉