Medium killer sudoku — play free online

100,000 medium puzzles, every one verified to have exactly one solution: the classic experience. No training wheels, but honest cages that reward the standard toolkit.

Cages of 2–4 cells with no revealed digits. Combination knowledge and the occasional rule-of-45 spot will see you through — keep the cheat sheet handy.

Puzzle numbers are permanent — #4,821 is the same puzzle for everyone, forever — so you can send a friend a link and race them. Progress saves automatically in your browser, pencil marks tidy themselves, and there's a dark mode for late-night solving.

Not sure this is your level?

Try the daily puzzle — difficulty rotates through the week, easy on Mondays through expert on Sundays, so you can find your ceiling one day at a time.