Sudoku Solver
Type your 9x9 puzzle into the grid and let the solver finish it. It runs a real backtracking algorithm right in your browser, shows the solve time and step count, and checks your entries for mistakes.
Enter your puzzle
Only digits 1 to 9 are accepted. Leave unknown cells empty. Your original numbers stay dark and bold; the numbers found by the solver appear in blue.
How to use this solver
- Enter the puzzle. Type the given digits 1 to 9 into the matching cells and leave the rest empty.
- Check it first (optional). Press Validate to catch duplicate digits in any row, column or 3 by 3 box before solving.
- Press Solve. The backtracking solver fills the grid, highlights its own answers in blue, and reports the solve time and step count.
- Start over anytime. Press Clear to empty the grid, or Load Sample Puzzle to try a ready made puzzle.
Frequently Asked Questions (FAQ)
How do I enter my Sudoku puzzle?
Type digits 1 to 9 into the empty cells of the grid and leave the unknown cells blank. Only digits 1 to 9 are accepted. You can also press Load Sample Puzzle to fill the grid with a ready puzzle.
How does the Solve button work?
Pressing Solve runs a real backtracking algorithm in your browser. It fills every empty cell, colors the solved cells blue while your original numbers stay dark and bold, and reports the solve time and the number of steps used.
What does the Validate button check?
Validate checks the grid for duplicate digits in rows, columns and 3 by 3 boxes and tells you exactly where the problem is. It also reports when the puzzle is valid but no solution exists.
Is my Sudoku puzzle sent to a server?
No. The whole solver runs in your browser on your own device. Nothing you type is sent anywhere or stored online.