CodeCrafters
Build your own Redis, Git or SQLite and pass tests at each stage
CodeCrafters has you build your own version of well-known software, step by step. Challenges include Redis, Git, SQLite, a shell, grep, Kafka, BitTorrent, an HTTP server, a DNS server and an interpreter. Each one is split into stages. You write code in your own editor, run git push, and tests check your work within seconds.
Freemium · Login needed · Terminal · Intermediate
About CodeCrafters
You learn how these systems work inside by building them yourself, in the language you choose. It suits developers with some experience who want serious projects.
There is a free plan for trying it out, with limited content. Full access needs a paid membership, sold as 3-month, yearly or lifetime plans. Team plans are also available.
On Breakpoint since 23 Oct 2026.