Sudoku X Sudoku Solver: Solve Diagonal Sudoku Online
Our free X Sudoku Solver solves diagonal Sudoku puzzles directly in your browser. Enter the givens, paste an 81-character puzzle string, or step through the answer one cell at a time. The solver applies the classic Sudoku rules plus the X Sudoku rule: both long diagonals must contain the digits 1 to 9 without repeats.
How to Use the X Sudoku Solver
- Fill the grid with the clues from your puzzle.
- Use 0 or . for blanks if you import a puzzle string.
- Click Solve for the full answer, or Step to reveal one cell.
- Check the uniqueness message to see whether the puzzle has one solution or more than one.
What Makes X Sudoku Different?
X Sudoku, also called Diagonal Sudoku, uses the normal row, column, and 3x3 box rules. It adds two extra units: the main diagonal from top left to bottom right and the anti-diagonal from top right to bottom left. Each diagonal must also contain every digit from 1 to 9 exactly once.
When This Solver Helps
- Check a difficult X Sudoku puzzle when you are stuck.
- Verify that a handmade diagonal Sudoku has a valid solution.
- Use Step mode to learn how diagonal constraints narrow candidates.
- Export the finished grid as a compact 81-character string.
Everything runs locally in your browser, so your puzzle is not uploaded anywhere.
Frequently Asked Questions
It is a solver for diagonal Sudoku puzzles. It follows the standard Sudoku rules and also checks that both main diagonals contain 1 to 9.
Yes. After solving, it counts solutions up to two and reports whether the X Sudoku has a unique solution or multiple solutions.
Use 81 characters read left to right and top to bottom. Digits 1 to 9 are givens, while 0 or . means an empty cell.