Codeforces is described as 'Website that hosts competitive programming contests' and is an app in the development category. There are more than 10 alternatives to Codeforces for Web-based, Self-Hosted, Mac and Windows. The best Codeforces alternative is HackerRank. It's not free, so if you're looking for a free alternative, you could try HackerRank or LeetCode. Other great apps like Codeforces are AceCoder, octree.io, Coderbyte and Spoj.
Shader Learning is an interactive browser-based platform for learning GPU programming through practical exercises. It offers over 250 challenges in GLSL and HLSL, allowing users to write and test shaders directly in the browser without any setup.
