Three difficulty levels
Easy leaves the most starting numbers, Medium leaves fewer, and Hard leaves the least, so you need more deduction to fill the grid.
Sudoku Generator
Generate a fresh 9x9 Sudoku puzzle in an instant. Pick a difficulty, fill it in with the number pad or your keyboard, and watch mistakes get flagged as you go.
How it works
Guaranteed unique solution
Every puzzle is checked with a solver before it's shown to you, so there is always exactly one correct way to finish it.
Live mistake checking
Conflicting numbers in the same row, column or 3x3 box are highlighted instantly as you type, so errors never pile up unnoticed.
FAQ
Does every generated puzzle have exactly one solution?
Yes. Cells are removed from a completed grid one at a time, and each removal is only kept if the puzzle still solves to exactly one valid grid. This is verified with a solver before the puzzle is shown to you.
Are my progress and best times saved anywhere besides this device?
No. Best times are saved only in your browser's local storage on this device. Nothing is uploaded to a server or shared anywhere else.
How do the difficulty levels differ?
Difficulty is controlled by how many starting clues remain. Easy leaves the most given numbers, Medium leaves fewer, and Hard leaves the fewest, which means more logical deduction is needed to solve it.