LeetCode is described as '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' and is a Code Learning service in the development category. There are more than 50 alternatives to LeetCode, not only websites but also apps for a variety of platforms, including Windows, Mac, Android and SaaS apps. The best LeetCode alternative is exercism, which is both free and Open Source. Other great sites and apps similar to LeetCode are Codecademy, HackerRank, Project Euler and Codewars.