Copy your puzzle (newspaper, book, printed grid…). The solver checks your input, then explains the solution step by step.
Other ways to enter a puzzle
It appears above each grid, for example “HAR 07397”.
81 cells, row by row: the digits, and 0 or . for empty cells. Ctrl+V anywhere on the page works too.
A sudoku solver that explains, not just one that gives the answer
Copy a puzzle from a newspaper, a book or the web: the Sudoku-Land solver doesn't just fill it in. It shows you every deduction, in order, with the name of the technique used and the cells that justify it. A good way to understand where you got stuck, and to get better from one puzzle to the next.
How it works
- 1. Enter the puzzle — with the keyboard, the number pad or the ring. Digits already in the row, column or block are greyed out, which prevents many typing mistakes.
- 2. The solver checks as you type — the message turns green when the puzzle has a single solution, orange if it has several, red if it has none. The faulty digit is shown in red.
- 3. Follow the solution step by step — click “Solve”: the difficulty is estimated, then each step is shown with its explanation and a link to learn the technique. You can also show the whole solution at once.
Tip: while entering the puzzle, tap a digit in the grid to see where it is already placed and which cells it can still go in.
Stuck on a printed puzzle?
Every grid on the Print sudoku puzzles page has a QR code and a code such as “HAR 07397”. Scan the QR code with your phone, or type the code in “Other ways to enter a puzzle”: the exact grid appears, with nothing to copy.
Already filled part of it in? ✏️ My digits turns on by itself: copy your digits (in blue), then ✓ Check tells you whether they are right. Solving starts from your correct digits.
From singles to forcing chains
The solver first uses the 17 techniques of the Sudoku-Land scale, the ones that rate our puzzles from Easy to Evil: singles, pairs and triples, X-Wing, XY-Wing, Swordfish… They are presented level by level in Techniques by level.
For tougher puzzles, it moves up to the “Extreme” level: XYZ-Wing, W-Wing, alternating inference chains and forcing chains. That way it cracks almost any puzzle by logic, including the famous AI Escargot. If no technique can move forward any more, it tells you clearly and finishes with backtracking.
Frequently asked questions
Is the sudoku solver free?
Yes, completely free and with no sign-up. Your input is kept in your browser: if you close the page, you'll find it again when you come back.
Can I get a simple hint without seeing the solution?
Yes. Turn on 💡 Progressive hints: each step is revealed in three stages — where to look, which technique to use, then the answer. Stop whenever you like.
What if my puzzle has several solutions, or none?
The solver warns you as you type: in orange if the puzzle has several solutions, in red if it has none. It is almost always a copying mistake: check the digits it points out. Only a puzzle with a single solution can be solved step by step.
What is backtracking?
The computer tries a digit, carries on, and goes back if it reaches a dead end. This method always finds the solution, but it is not reasoning: cells found this way are shown in grey, without explanation. The solver only uses it once all its techniques are exhausted, and it tells you so.
How do I continue a puzzle I've already started?
Enter the starting grid, then turn on ✏️ My digits and copy the digits you have found. ✓ Check compares them with the solution, and ▶ Solve starts from your correct digits, ignoring the wrong ones.
How do I find out how hard my puzzle is?
When solving starts, the solver shows the estimated level on the Sudoku-Land scale: Easy, Medium, Hard, Expert or Evil — or “Extreme” if the puzzle needs more advanced techniques. With 🧩 Auto-fill on, it appears as you type, as soon as the puzzle can be finished by logic.