SPOJ

SPOJ, which stands for Sphere Online Judge, is one of the most comprehensive coding libraries available. This website includes over 20,000 coding challenges and sometimes offers incentives such as gift cards and prizes to winners. Although not every official coding solution is put on the forum, their discussion boards are a great place to discover new coding skills.

The SPOJ platform is built on an online judge system that automatically evaluates user-submitted programs. Support for over 45 programming languages and compilers, including C, C++, Pascal, JAVA, C#, Perl, Python, Ruby, Haskell, Ocaml, and esoteric languages, is one of its most notable features. A rapidly growing problem-set of over 13000 tasks available for practice 24 hours a day (in English, Polish, Vietnamese, Portuguese, and other languages), including many original tasks prepared by the project's community of professional problem-setters.

It is also a user-friendly browser-based content management system that allows people to set up their own contests in minutes and use the tasks currently offered by the system. A flexible testing system that allows for dynamic interaction with submitted programs and fully customizable assessment result output.

Website: spoj.com