
Codeforces
5.9#23 in coding challenge platformsFree planFree planWebAPI
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Codeforces suits programmers who want to compete, track contest ratings, or practice with previous contests. Its API may also suit users seeking machine-readable access to some public data.
It suits hiring teams that want to assess skills and personality, with custom assessments, proctoring, and detailed reporting. The Free plan is geared to small volumes, while the listed Startup and Enterprise plans provide larger invite and admin allocations.