Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

yank

Marking a published crate version so new projects won't pick it, without deleting it.

cargo yank --version X stops new Cargo.lock files from choosing that version; existing lock files that already use it keep working.