HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.
LeetCode - Practice and level up your development skills and prepare for technical interviews.
iMocha - Make intelligent talent decisions.
Edabit - Learn to Code in 90 Days or Less
Codility - Codility provides a SaaS platform with advanced validation, security and protection features to evaluate the skills of software engineers.
Codewars - Achieve code mastery through challenge.