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Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.

CodinGame is a challenge-based training platform for programmers where you can play with the hottest programming topics.

The programmer testing solution that matches your job descriptions and helps you hire great developers faster.

Devskiller is an online testing platform that helps companies verify programming skills. It’s designed to directly address the key problems of hiring the IT talent: • Programming skills quality assessmentDevskiller helps to verify tech skills of programming languages, frameworks and libraries, imitating a real programming environment.• Customized online testingAssessing candidates at the first screening step results in a smaller, better-qualified and suited IT candidate pipeline before the time-consuming process of interviewing.• HR user-friendly toolDevskiller is easy to use for staff with no technical background, decreasing high costs of engaging the tech team.• EducationDevskiller helps also to evaluate the progress of education of programmers.In short, our customers use the platform to reduce the number of unnecessary interviews by 60-70% and to decrease the time-to-hire by 30-50%. »

Duel with friends and foes in head-to-head programming battles!

Coderbyte is a place built for anyone to practice and perfect their programming skills. Challenges are added almost every day so you can work on applying your algorithmic thought process on any problem you want at anytime. Coderbyte is built on improving your ability to work on common logic, mathematical, and algorithmic problems you might one day encounter.

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

SPOJ (Sphere Online Judge) is an online judge system with over 315,000 registered users and over 20000 problems. The solution to problems can be submitted in over 60 languages including C, C++, Java, Python, C#, Go, Haskell, Ocaml, and F#. SPOJ has a rapidly growing problem set/tasks available for practice 24 hours/day, including many original tasks prepared by the community of expert problem setters associated with the project.

CheckiO is expanding the world’s code literacy through gameplay.

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

Develop your coding skills and practice them by competing with hundreds of players worldwide. Code your own bots in your preferred language and join the various competitions that we offer. Learn, win prizes, but most importantly, have fun coding! Check out the our current competitions to see how you could get started.

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

At Geektastic we help our client's thoroughly evaluate their future talent using our unique peer reviewed code challenge platform. We believe a candidate is worth more than a score and the only way to thoroughly understand how suitable they are to work in your team is to have a human look over their code. The platform allows clients to license code challenges from our portfolio or upload their own, they can also choose to have our on-demand team (of exceptionally talent software engineers) carry out the thorough review or perform it in-house. »

We provide a way to track progress of many different tools developers use and turn it into an achievements and leaderboard based game. It makes work at a software company similar to playing multiplayer game. Our test group showed that developers (especially those who consider themselves gamers) gain extra productivity and it keeps them motivated and focused on their tasks.