Sudoku Solver
Enter Sudoku givens and solve the grid locally with backtracking.
Enter the given digits, then press Solve. Blank cells are allowed.
Solve a Sudoku grid
This Sudoku Solver uses a standard backtracking search after checking the givens for conflicts. Fill in the numbers you know, leave unknown cells blank, and press Solve. If the givens are consistent and a solution exists, the missing cells are filled into the grid.
The solver is useful when you are stuck and want to inspect one complete solution. It does not explain human solving strategies step by step, so a puzzle that is solvable by logic and a puzzle that requires guessing are both handled by the same search.
Type the digits you already know, leave the rest blank, and press Solve. The solver tints every cell it filled so you can tell your givens from its answers, and it reports a conflict instead of guessing when your starting numbers cannot work.
Local puzzle solving
The grid never leaves your browser. A small local counter records solved sessions, but no puzzle is uploaded or saved remotely. If you care about uniqueness, verify the puzzle with a dedicated uniqueness checker after solving.
Frequently Asked Questions
How does the solver work?
It first checks your givens for row, column, and box conflicts, then fills the rest with a backtracking search and tints the cells it added.
What if it says no solution?
That means the digits you entered cannot form a valid grid, usually a mistyped given, so double-check the numbers you were sure of.
Does it show the steps or check for a unique solution?
No. It returns one complete solution rather than a human solving walkthrough, and it does not verify the puzzle has only one answer.
Does my puzzle leave the browser?
No. Everything is solved locally and nothing is uploaded.
Browser-based tests, solvers, and games you can use privately online.