Free Sudoku
Sudoku deals Easy, Medium, Hard and Expert puzzles with exactly one solution, graded by the human techniques they need. Hints name the technique and explain the step, the Solver tab checks any puzzle you type or paste, and Print PDF makes sheets with solutions. Use Notes for pencil marks, turn on Auto candidates or try the Daily puzzle.
- Levels:
- Easy, Medium, Hard, Expert
- Solver:
- Type or paste 81 characters
- Print:
- PDF sheets with solutions
- Price:
- Free
- Runs:
- Locally, in your browser
- Uploads:
- None: files never leave your device
- Account:
- Not needed
Quick answers
How are the difficulty levels decided?
Each puzzle is solved by a program that only uses human techniques. Easy needs only singles, Medium adds pointing pairs and box/line reductions, Hard needs pairs or triples, and Expert needs an X-Wing, XY-Wing or Swordfish.
Does every puzzle have a single solution?
Yes. Every puzzle is checked by a solver that counts solutions, and the hints never need guessing.
Processed on your device: your files are never uploaded. How it works
Network activity in this tab
What this page has requested since you opened the site in this tab. An upload is any request that sends data: POST, PUT, PATCH or a request with a body.
No uploads: nothing has been sent from this page.
No network requests yet.
To see every request, open your browser's developer tools (Network tab).
How to use the Sudoku
- Choose a difficulty (or today's daily puzzle) and select a cell with the mouse, a tap or the arrow keys.
- Type or tap a digit to fill it. Switch on Notes (or hold Shift) to pencil in candidates, or turn on Auto candidates.
- Use Hint when stuck: it names the technique, highlights the cells involved and explains the step, which you can apply.
- In the Solver tab, type or paste any puzzle to check that it has one solution and walk through the logic step by step.
- In Print PDF, choose difficulty, puzzles per page and pages to download a printable sheet with solutions.
Credits & open source
Our own code plus open-source libraries. Thank you to the people who make these projects.
- jsPDFPDF generation in the browser. © James Hall, yWorks GmbH and contributors · MIT
- fflateFast ZIP compression for batch downloads. © Arjun Barrett · MIT
Web platform APIs used: Keyboard Events, Pointer Events, localStorage, Clipboard API, File API.
Full license texts: third-party notices · all credits
Frequently asked questions
What is the difference between conflicts and mistakes?
Conflicts only flag digits that repeat in a row, column or box. Mistakes compares your digits with the real solution, so wrong digits show up immediately.
Can I solve a puzzle from a newspaper?
Yes. Open the Solver tab and type it in or paste 81 characters (dots or zeros for empty cells). It tells you whether the puzzle has one solution and shows the steps.
Is my game saved?
Your current puzzle for each difficulty, the daily puzzle and your best times are saved in this browser, and the clock pauses while the tab is hidden.