Cratery

Cratery is a free Rust quiz site. Each question is a short Rust snippet with multiple choice answers, and every answer comes with a full explanation of the Rust rule behind it.

Reading about ownership and lifetimes only goes so far. Cratery turns those rules into small puzzles that take a minute to answer, with an optional hint first.

Questions are grouped into topics such as ownership, lifetimes, traits, concurrency, smart pointers, error handling and the borrow checker. Forge Trials is a browser editor for writing Rust and running tests as you go. Code runs on Cratera, so every answer with code runs in a real sandbox. No account is needed, and progress saves in the browser.

Anyone can write a quest and share it at its own link. There is a daily question, a weekly contest, ranks from Novice to Grandmaster and a leaderboard. A Discord bot brings the daily question to Discord with /daily.

680+ questions. 19K+ answers. 240+ registered users.

Try it at cratery.cratera.org. The code is on GitHub.