Sudoku
Play Sudoku free in your browser — no download and no sign-up. Choose easy, medium or hard, pencil in candidate notes, and use a hint whenever a puzzle stalls.
Sudoku is the world's most popular logic puzzle. You fill a 9×9 grid so that every row, every column and every 3×3 box holds the digits 1 to 9 exactly once. There is no arithmetic involved — only step-by-step deduction — which is exactly why a single puzzle can keep you absorbed for ten quiet minutes.
Why Play Sudoku Here
Every puzzle runs straight in your browser. There is nothing to install and no account to open — load the page and the grid is ready, on a phone, tablet or desktop alike.
You get three difficulty levels, a Notes mode for pencil marks, instant red highlighting when two numbers clash, a running timer, and a hint that fills one correct cell. Every puzzle is generated with a single solution, so you can always finish by logic rather than guesswork.
How to Play Sudoku Online
Tap a cell, then type a digit or tap the on-screen keypad to fill it in. Turn on Notes mode to pencil several candidates into a cell while you narrow down the answer.
Numbers that break a row, column or box turn red the moment you place them, so mistakes never hide for long. The timer tracks your pace, and a single hint unblocks you without solving the rest of the board.
Sudoku Rules
The grid splits into nine rows, nine columns and nine 3×3 boxes. Each of these groups must contain the digits 1 through 9 with no repeats.
The starting clues are fixed and cannot be changed. Because every puzzle we generate has exactly one solution, it is always solvable by reasoning alone — you never need to guess.
Solving Techniques
Begin with 'naked singles' — cells where only one digit can possibly fit. Then take each number in turn and scan rows, columns and boxes to find the one spot it must occupy, known as a 'hidden single'.
On harder grids, use Notes to record candidates, then look for pairs: when two cells in a row, column or box can only hold the same two numbers, those digits can be ruled out everywhere else in that group.
Sudoku Tips
- Scan for the numbers that already appear most often; they are the easiest to place next.
- Use Notes to record candidates instead of holding them all in your head.
- Work the row, column or box that already has the most clues — it gives the quickest wins.
- When two cells in a box share the same two candidates, erase those digits from the rest of the box.
- Truly stuck? One hint reveals a correct cell and restarts your chain of logic without spoiling the puzzle.
Frequently Asked Questions
Is this Sudoku free to play?
Yes. Every puzzle is free in your browser, with no download and no sign-up — just open the page and start.
Does every puzzle have a unique solution?
Yes. Our generator guarantees exactly one solution per puzzle, so it can always be solved by logic without guessing.
Do I need to be good at math?
No. Sudoku is pure logic — the digits could be any nine symbols and the puzzle would work the same.
What do the difficulty levels mean?
Easy grids start with more given numbers; medium and hard give fewer clues and call for deeper deduction.
Can I use pencil marks?
Yes. Switch on Notes mode to pencil candidate numbers into a cell, then clear them as you confirm the answer.
What does the hint button do?
It fills in one correct cell — the one you have selected if it is empty, otherwise a random empty cell — so you can get moving again.
Is my solving time tracked?
Yes. A timer counts up while you solve so you can race your own best pace, but there is no pressure to finish quickly.
