What about HackerRank?
Is HackerRank is good online judge?
HackerRank is good for beginners. It doesn't create much trouble for input formats before accepting answers. Online Judge will be good for advanced level, specially if you want to be prepared for programming contests.
www.codewars.com On behalf of @cheeze
It's a site for hackers from all over da world to solve prog problems in different CS domains like algorithms, machine learning and artificial intelligence, and to excel in different prog paradigms like functional prog. it's a good place to learn from and ofcourse not A ONLINE JUDGE!!