Sudoku frequently asked questions

Yes. Sudokumee is designed as a free online Sudoku experience with modes, difficulty levels, notes, undo and hints. There are no ads and nothing to buy.

Classic Sudoku is a 9×9 puzzle where every row, column and 3×3 box contains digits 1–9 without repeats.

Diagonal Sudoku adds a rule requiring both long diagonals to contain 1–9 without repeats.

Killer Sudoku adds dashed cages with target sums. Digits within a cage cannot repeat and must add up to the target.

In Killer Sudoku the cage sums supply most of the clues, so a puzzle needs far fewer given digits than a Classic one.

Yes. The puzzle generator checks every puzzle for a single valid solution before presenting it. Killer puzzles are checked against their cage sums as well.

No. A hint explains the logic behind a next move, such as a naked single, a hidden single or a cage combination, and you choose whether to apply it. If a wrong digit is on the board, the hint points that out first. In rare cases where no simple pattern exists, the hint says that it is revealing the digit directly.

Yes. Your current game in each mode is saved in your browser on this device, so you can close the tab and continue later. Saved games are not synced between devices, and clearing your browser data removes them.

Yes. The responsive interface is designed for touch screens as well as desktop keyboard controls.

No account is required to start playing.

Sudoku exercises logical thinking, working memory and pattern recognition, since each move requires holding several possibilities in mind while checking them against the rules. Like any mental puzzle, regular practice can help keep those skills sharp, though it isn't a substitute for medical advice on brain health.

See the Privacy Policy for information about the site's data practices.

Yes. Use the printer button on the game board to print your current puzzle, or make a whole set on the printable Sudoku page, with an optional answer key.