- Codewars: https://www.codewars.com/
- HackerRank: https://www.hackerrank.com/dashboard
- CoderByte: https://coderbyte.com/developers
- leetCode: https://leetcode.com/
- geeksForGeeks: https://www.geeksforgeeks.org/
- CodingNinjas: https://www.codingninjas.com/
- freeCodeCamp: https://www.freecodecamp.org/
- codeChef: https://www.codechef.com/practice
- hackerEarth: https://www.hackerearth.com/for-developers/
- Geektastic: https://geektastic.com/