Sudoku Checker

Validate 9x9 Sudoku puzzles instantly. Checks rows, columns, and 3x3 subgrids for correctness.

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About This Tool

This online Sudoku Checker allows you to validate any 9x9 Sudoku puzzle for correctness. Simply enter numbers 1-9 into the grid (use 0 or leave blank for empty cells), and the tool will check if the puzzle follows all Sudoku rules: each row must contain digits 1-9 without repetition, each column must contain digits 1-9 without repetition, and each 3x3 subgrid must contain digits 1-9 without repetition. The tool provides immediate visual feedback highlighting any errors and gives a detailed validation report.

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How to Use

Enter numbers 1-9 into the 9x9 grid (use 0 or leave blank for empty cells)
Click the 'Check Sudoku' button to validate the puzzle
View the results showing which rows, columns, or subgrids have errors
Use the 'Clear Grid' button to reset and start over
For a valid puzzle, you'll see a success message with completion details

Frequently Asked Questions

Find Quick Answers

What numbers should I enter for empty cells?

You can enter 0 or leave the cell blank to represent empty cells in your Sudoku puzzle.

Does this tool solve Sudoku puzzles?

No, this tool only validates existing Sudoku puzzles. It checks if a partially or fully completed puzzle follows all Sudoku rules without solving it.

What Sudoku rules does this checker validate?

The tool validates three rules: 1) Each row must contain digits 1-9 without repetition, 2) Each column must contain digits 1-9 without repetition, 3) Each 3x3 subgrid must contain digits 1-9 without repetition.

Can I check partially completed Sudoku puzzles?

Yes, the tool works with both partially completed and fully completed Sudoku puzzles. It will validate all filled cells according to Sudoku rules.

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