Sudoku Solver Online
Enter a Sudoku puzzle, check whether it is valid, get the next forced logical move, or solve a puzzle with a unique solution. Everything runs in your browser.
Validate first, then ask for the smallest useful amount of help
Use Validate to catch duplicate digits and determine whether the current grid has no solution, one unique solution, or multiple solutions. A proper published Sudoku should normally have exactly one solution.
Use Next step when you want to keep solving yourself. The tool looks for a forced placement such as a naked single or hidden single before suggesting a full solution.
Sudoku Solver questions
Can this Sudoku Solver detect an invalid puzzle?
Yes. It checks duplicate digits in every row, column and 3×3 box, then searches for completions. It reports no solution, one unique solution, or multiple solutions.
Does the Sudoku Solver work without uploading my puzzle?
Yes. The solving logic runs in your browser. You can type, paste, validate and solve a grid without sending the puzzle to a Sudoku solving API.
What does Next step do?
Next step looks for a forced placement using basic human-readable logic, starting with naked singles and hidden singles. If those are exhausted, it points you toward more advanced solving techniques instead of pretending a guess is logical.
Why does the solver say a puzzle has multiple solutions?
The current clues allow more than one valid completed grid. Add more correct clues or check whether a clue was omitted. A standard published Sudoku is normally expected to have exactly one solution.
What format can I paste into the Sudoku Solver?
Paste 81 cells using digits 1–9 for filled cells and 0 or a period for empty cells. Spaces and line breaks are ignored.