CSSBattle http://www.rosettacode.org/wiki/Rosetta_Code Codier – Front-end Coding Challenges Frontloops - Frontend development challenges Frontend Practice | Become a better frontend developer. Ace Front End GitHub - felipefialho/frontend-challenges: A public list of open-source challenges from companies around the world Code Golf 100 Days CSS Challenge Firecode.io CodeAbbey Exercism Binary Search CheckiO Codewars Codility CodingBat (Java/Python) cyber-dojo Edabit // Learn to Code with 10,000+ Interactive Challenges Gendou.com Cryptography Challenges Project Euler Programmr | Get Better At Programming ROSALIND (Bioinformatics) The Cryptopals Crypto Challenges The Python Challenge

Courses

CodeGuppy | JavaScript for kids and teens Codecademy CodeGym (Java) SoloLearn JetBrains Academy CodeHS 🎓 Codeasy.net (C#)