Achieve code mastery through challenge. Improve your skills by training with others on real code challenges

Kata In our dojo, ...

CodeChef was created by Directi as a way to continuously challenge and engage the developer community. Our goals are to provid ...

A fun social platform for hackers to solve interesting puzzles, build quick hacks, code game bots and collaborate to solve rea ...

Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathemati ...

Learn to code (for free) with interactive challenges. Gain XP, unlock achievements and climb the leaderboard. It's the fastest ...

VIM Adventures is an online game based on VIM's keyboard shortcuts (commands, motions and operators). It's the "Zelda meets te ...

LeetCode is a platform for learning and improving coding skills with the goal of being fully prepared for programming intervie ...

Screeps is a massive multiplayer online real-time strategy game. Each player can create his or her own colony in a single pers ...

Topcoder gathers the world’s experts in design, development and data science to work on interesting and challenging problems. ...

This version of Ruby Warrior is a project by Bloc, a part-time online coding bootcamp for people who want to keep their curren ...

SPOJ (Sphere Online Judge) is an online judge system with over 315,000 registered users and over 20000 problems. The solution ...

CodeEval is platform for hosting coding challenges which has over 20,000+ competitive developers.

Coderbyte is a place built for anyone to practice and perfect their programming skills. Challenges are added almost every day ...

CodeSignal is the leading provider of assessments for technical recruiting. As the creator of the Predictive Coding Score, Cod ...

CheckiO is expanding the world’s code literacy through gameplay. We always wanted to create the most entertaining game where g ...