Play Sudoku Online — Free Classic Sudoku
Dealing a puzzle…
How to play
The rules of sudoku, in one minute
Fill the 9×9 grid so that every row, every column and every 3×3 box contains the numbers 1 to 9 exactly once. Some numbers are given to start; the rest you deduce with logic — no math, no guessing.
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Tap a cell, then a number
Or use the arrow keys and 1–9 on a keyboard.
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Notes
Turn on notes (N) to pencil in candidates. Placing a number clears it from the notes around it.
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Mistakes
A wrong number turns red and counts as a mistake — there is no limit, so keep going.
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Hints
Three per game. A hint fixes a wrong entry first, then reveals the next logical cell.
Frequently asked questions
Is this sudoku free to play online?
Yes. Every puzzle is free, with no sign-up and no download. Your game is saved in your browser, so you can close the tab and pick up where you left off.
How many puzzles are there?
A thousand hand-checked puzzles for each of the four difficulty levels — Easy, Medium, Hard and Expert. Every one has exactly one solution and can be solved with logic alone, no guessing.
What do the difficulty levels mean?
Easy puzzles fall to naked singles. Medium needs hidden singles. Hard brings in pairs, triples and pointing pairs. Expert puzzles require X-Wing, Swordfish or XY-Wing.
Are there keyboard shortcuts?
Arrow keys move, 1–9 place a number, Backspace erases, N toggles notes, Z undoes, H gives a hint and Space pauses.
Is there an app?
One Sudoku is free on the App Store and Google Play, with a daily challenge, streaks, statistics and leaderboards, and it plays fully offline.