Spoj is an online judge system with over 315000 registered users and over 20000 problems. Developed by Sphere Research Labs
License: Free
Spoj is ideal for competitive programmers looking for a wide range of algorithmic challenges, while CodinGame offers a more engaging and gamified platform for learning and practicing coding through games and multiplayer challenges. The two platforms cater to different needs, with Spoj focusing on problem-solving and coding contests, and CodinGame emphasizing learning through interactive experiences.