Sudoku
Nine rows, nine columns, one logical answer.
Sudoku
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About Sudoku
Sudoku is the world's favorite logic puzzle, and every board here is freshly generated with a guaranteed unique solution. Fill the 9×9 grid so each row, column, and 3×3 box contains the digits 1-9 exactly once. Choose Easy for a relaxed solve, Medium for a proper think, Hard for puzzles that demand real technique, or Expert for the sparsest grids — and come back every day for the Daily puzzle, the same board for everyone, to build a solving streak. Pencil marks let you note candidates the way you would on paper, conflicts are highlighted as you type, and three hints are on hand when you're truly stuck. With keyboard support, a timer, and clean highlighting of matching digits, it's a paper-quality sudoku experience in your browser. Each solve earns up to three stars (a mistake or a hint costs one), stars unlock board themes from Paper and Ocean to Neon and Gold, finished rows, columns and boxes ripple as they complete, and your puzzle in progress is saved if you close the tab.
How to play Sudoku
- 1Tap a cell, then tap a number (or press 1-9 on your keyboard) to fill it.
- 2Each row, column, and 3×3 box must contain 1-9 with no repeats.
- 3Toggle pencil mode ✏️ to jot small candidate numbers in empty cells.
- 4Conflicting numbers are highlighted red the moment they appear.
- 5Stuck? Use one of your 3 hints to reveal the correct digit for a cell. Undo, Auto notes and pause (Esc) are there too.
- 6Solve with no mistakes and no hints for ★★★ — stars unlock new board themes.
Tips & strategy
- Start with rows, columns, or boxes that already have 6+ digits filled.
- Scan one number at a time across the whole grid — where can the 7s go?
- Use pencil marks for cells with only two candidates, then hunt for pairs.
- If a number's spots in a box all fall in one row, exclude that row elsewhere.
- Play the Daily puzzle each day to keep your streak alive.
Frequently asked questions
Does every puzzle have exactly one solution?
Yes — the generator verifies uniqueness before serving a puzzle, on every difficulty.
What's the difference between difficulties?
Easy gives you around 38 starting digits, Medium about 32, and Hard as few as 26 — fewer givens demand deeper logic.
Can I play Sudoku with my keyboard?
Yes — arrow keys move between cells, 1-9 fills, Backspace erases, and P toggles pencil mode.