Sudoku Solver
Stuck on a Sudoku? Enter the numbers you can see, press Solve, and the solver fills in every empty cell. It also warns you if the numbers you typed break the rules or if the puzzle has more than one solution.
Tap a cell, then type 1–9. Use Backspace or 0 to clear a cell.
How to use the Sudoku solver
- Click a cell in the grid and type the number from your puzzle. Repeat for every given number.
- Press Solve. The solver fills in all the empty cells using fast backtracking search.
- Compare the answer with your own grid to find your mistake, or to learn which cell you should have filled first.
- Press Clear to start over, or Load example to see how it works.
Sudoku solver FAQ
- Is this Sudoku solver free?
- Yes. It is completely free, needs no sign-up, and runs in your browser, so the puzzle you enter never leaves your device.
- What if my puzzle has no solution?
- The solver tells you. This almost always means a number was typed in wrong — look for the highlighted conflicts and compare with the original.
- Can it solve the hardest Sudoku puzzles?
- Yes. The solver uses a complete search, so it solves any valid 9×9 puzzle, including the ones marked expert or extreme, in a fraction of a second.
- What does 'more than one solution' mean?
- A proper Sudoku has exactly one answer. If you see this message, a clue is probably missing or mistyped. The solver still shows you one valid way to finish the grid.