CodeFights is a San Francisco based technology startup on a mission to discover, develop and promote technical talent. It applies core game mechanics to transform practicing skills like programming into a fun and addictive game while helping talented people from all backgrounds to find amazing new opportunities.
This looks great. Built by CodeFights, which is a great place to work on your programming in a number of languages, with daily challenges, head-to-head battles and company bot battles that can land you jobs at big tech companies like GoDaddy, Uber and DropBox.
CodeSignal