Takehome - Effective and humane coding challenges for candidates
hackattic - No nonsense, real world programming challenges
Frontloops - Level up your frontend skills with handcrafted tasks
Code Fight Club - A fight club you can talk about. Less punching, more coding.
NPMPM - Do you have what it takes to find words that aren't NPM repos, yet?
Codewars - Achieve code mastery through challenge.