HackerPen - What is HackerPen?
FaceCode - Hire top tech talent with video interviews
HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.
Daily Coding Problem - Get exceptionally good at coding interviews
HackerEarth - HackerEarth is the network of top developers across the world. They connect to start-ups, tech companies, organizations and discover the best developer jobs. They participate in programming challenges and compete against other top developers.
Codewars - Achieve code mastery through challenge.