WorksHub - Helping Software Engineers find paid work, learn and get hired through Open Source contributions. WorksHub is made up of computer scientists, machine learning experts and the best in talent acquisition.
hackattic - No nonsense, real world programming challenges
Hacker Noon - How hackers start their afternoons.
Codewars - Achieve code mastery through challenge.
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.
Real Dev - Real-life coding skill challenge