The best free alternative to Coderbyte is freeCodeCamp, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Coderbyte and loads of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Coderbyte are Codecademy (Freemium), Coursera (Freemium), SoloLearn (Freemium) and W3Schools (Free).
LeetCode is a platform for learning and improving coding skills with the goal of being fully prepared for programming interviews. Choose problems to solve from categories such as System Design, Algorithms and Database, join code contests and engage in mock interviews.