Sudoku
Classic number puzzle.
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About Sudoku
Play a full game of Sudoku right in your browser. Each new game generates a fresh, fully solved 9x9 grid and then carves out cells to match your chosen difficulty, so every puzzle has exactly one correct solution. Fill the blanks with digits 1 to 9, check your work, or reveal the answer whenever you like.
This Sudoku tool is completely free with no sign-up, ads, or limits. Everything runs locally in your browser, so puzzles generate instantly and nothing you type is ever sent to a server. Pick Easy, Medium, or Hard, and the tool tells you the moment you have won.
Frequently asked questions
- Is this Sudoku game free to use?
- Yes, it is completely free. There is no sign-up, subscription, download, or usage limit. You can generate and solve as many puzzles as you want at no cost.
- Is my activity private?
- Yes. The entire game runs in your browser using JavaScript. Puzzles are generated on your device and your entries never leave your computer or get sent to any server.
- How does the difficulty setting work?
- Difficulty controls how many starting numbers (clues) are revealed. Easy leaves about 40 clues, Medium about 32, and Hard about 26. Fewer clues means you have to deduce more of the grid yourself.
- Does every puzzle have a unique solution?
- Yes. When cells are removed to create the puzzle, the generator verifies that only one valid completion remains, so there is always exactly one correct answer that matches the solution.
- What do the New Game, Check, and Solve buttons do?
- New Game creates a fresh puzzle at the selected difficulty. Check highlights in red any cells that break Sudoku rules or differ from the solution. Solve fills in the complete correct grid for you.
- How do I win, and does it work in dark mode?
- You win automatically the moment every cell matches the solution, and a completion message appears. The grid uses theme-neutral borders, so it stays clear and readable in both light and dark mode on desktop and mobile.