Sudoku Solver
Enter the given numbers from your puzzle, leave unknowns blank, and press Solve. The solver uses a backtracking algorithm to find the unique solution instantly.
Click a cell and type 1–9 to fill it in. Use arrow keys to navigate. Leave unknowns empty, then press Solve.
How to Use
- 1. Enter given numbers — Click any cell and type a digit (1–9). Use arrow keys to move between cells.
- 2. Leave unknowns empty — Blank cells are the ones the solver will fill in.
- 3. Press Solve — If the puzzle is valid, the solved digits appear in blue. Original given numbers stay white.
- 4. Edit or Clear — Press Edit to go back to your input, or Clear All to start fresh.
About Sudoku
Sudoku is a 9×9 number-placement puzzle. The goal is to fill every row, column, and 3×3 box with the digits 1–9 exactly once. A well-formed puzzle has exactly one solution. Our solver uses a depth-first backtracking algorithm that tries each digit in order and backtracks whenever a conflict is detected — typically solving any valid puzzle in milliseconds.