CodeCrafters

CodeCrafters is a platform of staged programming challenges that have users rebuild real software systems from scratch, including Redis, Git, SQLite, Shell, Kafka, grep, BitTorrent, HTTP server, DNS server, an interpreter, and Claude Code. Each challenge is divided into stages, and users work in their own language and IDE rather than a browser-based editor.

Work is submitted through a git push workflow that runs tests and returns results and hints. Challenges cover topics such as TCP servers, HTTP and Redis protocols, distributed systems and message queues, regular expressions, tokenization and ASTs, peer-to-peer networking, and LLM APIs with tool calling and agent loops. Work can be shared on GitHub.

CodeCrafters is aimed at experienced developers. It is packaged as a free plan with limited content and community features, a Membership for individuals with no content limits, Turbo tests, code examples, anonymous mode, perks, and priority support, and a Teams edition for groups of five or more that adds seat reassignment, a team leaderboard, usage analytics, and a Slack app. Membership plans are available on three-month, one-year, and lifetime terms; team seats are swappable and billed annually.