Sudoku Solver
Short answer: type your puzzle into the grid, or paste it as text, and press Solve. You get every move in order — naked single, hidden pair, X-Wing — with the reasoning behind it, not just the finished grid. Nothing is uploaded; the whole solver runs in your browser.
Paste a puzzle
Click a cell and type a digit, or paste all 81 cells below. Dots, zeros and dashes all count as empty, and line breaks are ignored — paste it however you have it.
The solution, one move at a time
Each move names the technique it used. Select a move to see the grid as it stood at that moment, with the candidates it reasoned over.
The same grid, without the numbers
Flip the grid to Shapes and solve the same puzzle again. Nothing about the logic changes — a hidden single is a hidden single either way — but a circle is far easier to sweep a row for than a 1, because you recognise it instead of reading it. That is the whole idea behind form9: sudoku with nine shapes instead of nine digits. Free, no ads, no tracking, fully offline.
Frequently asked questions
Does my puzzle get uploaded anywhere?
No. The solver is a few kilobytes of JavaScript that runs entirely in your browser — there is no server to send anything to, and the site has no ads or trackers. You can turn off your connection after the page loads and it still works.
Why show the steps instead of just the answer?
Because the answer teaches you nothing. Most solvers hand you a completed grid, which ends the puzzle and leaves you no better at the next one. Naming the move — and showing which cells forced it — is the part you can actually take with you.
It says my puzzle has more than one solution. Did I type it wrong?
Usually, yes — a mistyped or missing clue is the common cause. A proper sudoku has exactly one answer, and this solver refuses to walk through an ambiguous grid, because any "step by step" explanation of one would be presenting a guess as deduction. Check your entry against the source and add anything missing.
What does "needs a technique beyond the fourteen taught here" mean?
The solver only uses moves this site explains: singles, pairs, triples, quads, locked candidates, X-Wing, skyscraper, two-string kite, XY- and XYZ-Wing, remote pairs and simple colouring. A small number of published puzzles need longer forcing chains or trial and error. Rather than quietly guess, the solver stops and says so — and still shows you the finished grid.
Can I share a puzzle with someone?
Yes. The address bar always holds the grid you are looking at, so copying the URL copies the puzzle. Send it to a friend and they open exactly the position you are stuck on.
Does this work on a phone?
Yes — the grid scales to the screen and the digit pad sits under it. That is worth saying because most sudoku solvers still do not: the best-known one on the web has no mobile layout at all.