🔍 Free tool
Sudoku Solver
Stuck on a puzzle? Type it in and get the next step explained — or the whole solution. Free, no account.
Tip: you can paste a whole puzzle — 81 digits, using 0 or a dot for the empty squares. Arrow keys move around the grid.
How to use it
- Type the numbers you already have into the grid. Arrow keys move around; you can also paste a whole puzzle as 81 digits.
- If two numbers clash, they turn red straight away — that usually means a typo before it means a hard puzzle.
- Press “Show me the next step” for one square at a time, with the reason it has to be that number.
- Press “Solve the whole grid” if you would rather just see the finished puzzle. The numbers it works out are shown in a different colour to the ones you typed.
Why this one
Most solvers just dump the finished grid at you, which answers the question but ends the puzzle. This one leads with the next single step and tells you why that square has to be that number — a square with only one candidate left, or the only square in its row, column or box where a number can go. That is usually all you needed, and you get to finish the rest yourself.
It also tells you the truth about your grid. If what you typed cannot be solved, it says so instead of guessing — and if it has more than one answer, it warns you, because a proper sudoku has exactly one and you have probably missed a clue. Everything runs in your browser: the puzzle never leaves your device, there is nothing to install, and there are no ads.
Frequently asked questions
Does it show the steps, or just the answer?
Both, and the steps come first. “Show me the next step” fills in one square and explains the reasoning; “Solve the whole grid” finishes the puzzle. Use whichever you actually want.
Can it solve any sudoku?
Any standard 9×9 sudoku with a valid solution, including the hardest ones. Where a puzzle needs a technique more advanced than single candidates, the step is still correct — the tool just tells you it worked that one out by solving rather than by simple logic.
What if it says my puzzle has no solution?
Almost always a typo — a number entered in the wrong square, or the same number twice in a row, column or box. Clashing numbers are highlighted in red as you type, so check those first.
What does “more than one solution” mean?
A proper sudoku has exactly one answer. If yours has several, a clue is usually missing or mistyped. The tool still shows you one valid solution, but it warns you first.
Is it free, and does it work on a phone?
Free, with no account and no sign-up, and yes — the grid works on a phone or tablet with the number keypad. There are no ads on this site.
Would rather play than solve someone else’s? Try our Sudoku — no ads, no timer unless you want one.