Best Free Coding Challenge Platforms

kodwai is a platform where developers solve real coding challenges on their own machine with their own AI coding agent (Claude Code, Cursor, or Codex) and get scored on how well they direct the agent, across three axes: Direction, Outcome, and Lift. Pick a ticket-sized challenge (a multi-tenant rate limiter, an idempotent ETL pipeline, a Raft-lite log), run npx @kodwai/cli@latest challenge <slug> to pull the problem, starter code and tests into a fresh git repo, solve it the way you actually work, then run npx @kodwai/cli@latest submit. The score is 0 to 100, and every signal cites evidence from your transcript, commits and test runs. Free for developers with a public profile and leaderboard. Hiring teams can run private real-world interviews and see how candidates work with AI agents: the prompts, the recovery, the verification, the result.

DojoCode is a community-driven platform that offers a variety of coding challenges and contests across different programming languages and skill levels. Our mission is to make coding education interactive, enjoyable, and accessible for everyone.