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Sudoku Solver
Type the numbers from your puzzle, or paste them, then solve it all at once or one step at a time. Each step says which technique finds the next number, so you can learn as you go.
Paused
Click a cell and type its number. Arrow keys move, Backspace clears.
First:
Then:
81 digits, row by row. Use 0 or a dot for empty cells.
The solver runs in your browser. Your puzzle isn’t sent anywhere.
About the Sudoku
The Sudoku solver finds the answer to any 9×9 puzzle in a moment, and can also go one step at a time. Each step names the technique a person would use, such as a hidden single or an X-Wing, and highlights the cells, so you can finish the puzzle yourself. It also tells you if a puzzle has a typo, no solution, or more than one solution, and how hard it is.
How to use it
- 1 Click a cell and type its number, or paste the whole puzzle into the box (use 0 or a dot for blanks).
- 2 Press “Next step” to see the next number and why it goes there, or “Solve” for the full answer.
- 3 Red cells mean two of the same number share a row, column or box: fix the typo first.
- 4 Press “Play this puzzle” to solve it yourself with notes, hints and a timer.
Frequently asked questions
How does the Sudoku solver work?
For the full answer it tries numbers cell by cell, always starting with the cell that has the fewest options, and backs up when it reaches a dead end. That takes milliseconds. For “Next step” it works like a person instead, using the simplest technique that finds or rules out a number.
Why does it say my puzzle has more than one solution?
A proper Sudoku has exactly one answer. If a clue is missing or was typed in the wrong cell, the puzzle can have many answers. Check your numbers against the original. The solver still shows one possible answer.
Why does it say there is no solution?
Usually a number was typed in the wrong cell. Even when no two numbers clash yet, a wrong clue can make it impossible to finish. Compare the grid with the original puzzle.
Which techniques can the step-by-step solver explain?
Naked and hidden singles, pointing pairs, box/line reduction, naked and hidden pairs and triples, X-Wing, Y-Wing and Swordfish. Very rare puzzles need chains beyond these; then the next number is simply revealed.
How do I paste a puzzle?
Paste 81 digits row by row, with 0, a dot or a dash for empty cells. Spaces and line breaks are ignored, so you can copy a puzzle from most websites and apps.
Is my puzzle sent anywhere?
No. The solver runs in your browser, so the puzzle never leaves your device.
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