Free puzzle game · No download · No sign-up
Play Sudoku online free.
A clean 9×9 puzzle in your browser — four difficulties, notes, hints, and a mistake counter. Just open the page and start solving.
The short answer: you can play Sudoku online free right now, no download and no sign-up: four difficulties from easy to expert, with notes, hints and a mistake counter, and every puzzle has exactly one solution.
01 — How to playFill every row, column and box with 1–9.
Sudoku is a logic puzzle, not a maths puzzle. You never need to add or multiply — you only need to work out where each digit belongs.
One digit per row, column and box
Every row, every column, and every 3×3 box must contain the digits 1 to 9 exactly once. No digit may repeat in any of them.
Tap a cell, then tap a number
Tap any empty cell to select it, then tap a number on the pad or press 1–9 on your keyboard. Blue numbers are the puzzle's givens and cannot be changed.
Use notes for candidates
Turn on Notes mode and tap digits to pencil in small candidates. When you place a number, that digit is automatically removed from the notes of every cell in the same row, column, and box.
Three mistakes and the game ends
A wrong entry turns red and counts as one mistake. At 3 mistakes the puzzle ends — retry the same puzzle or start a fresh one.
Win by completing the grid
Fill every empty cell correctly and you win. Your time, mistakes, and hints are shown, and your best time per difficulty is saved in your browser.
02 — TechniquesFour moves that solve most puzzles.
You do not need to guess. These four techniques carry you through easy and medium puzzles, and most of hard.
Naked singleWhen a cell has only one possible digit left, that digit goes there. Fill in all the notes first and the naked singles jump out.
Hidden singleWhen a digit can only go in one cell of a row, column, or box — even if that cell has other candidates — that digit goes there.
Pointing pairsWhen a digit's candidates in a box all sit in one row or column, that digit cannot appear anywhere else in that row or column.
Box-line reductionWhen a digit's candidates in a row or column all sit in one box, that digit cannot appear in the other cells of that box.
03 — Difficulty levelsWhat changes between levels.
Difficulty is set by how many starting numbers a puzzle has. Fewer givens means more empty cells — and more logic to work through.
| Difficulty | Givens | Empty cells | Who it is for |
|---|
| Easy | ~40 | ~41 | First-timers and a relaxed solve |
| Medium | ~32 | ~49 | Players who know the basics |
| Hard | ~27 | ~54 | Regular solvers who use notes |
| Expert | ~24 | ~57 | Experienced solvers who use all four techniques |
04 — FAQQuestions, answered first.
Short answers up front, details after.
Is it free to play Sudoku here?
Yes, it is completely free. Every puzzle is free to play, with no payment, no account, and no limit on how many puzzles you solve.
Do I need to download anything or sign up?
No. There is nothing to download and no sign-up. Just open the page, pick a difficulty, and start solving in your browser on phone or desktop.
What are the rules of Sudoku?
Every row, every column, and every 3×3 box must contain the digits 1 to 9 exactly once. Fill in the empty cells so that no digit repeats in any row, column, or box.
What are notes (pencil marks)?
Notes are small pencil marks you write in a cell to remember which digits could still go there. Turn on Notes mode, then tap digits to add or remove candidates. When you place a number, that digit is automatically removed from the notes of every cell in the same row, column, and box.
How many mistakes can I make?
You can make up to 3 mistakes. A wrong entry turns red and counts as one mistake. At 3 mistakes the game ends, and you can retry the same puzzle or start a new one.
What do the difficulty levels mean?
Difficulty is set by how many starting numbers a puzzle has. Easy starts with about 40 given digits, Medium about 32, Hard about 27, and Expert about 24. Fewer givens means more empty cells to reason about.
Does every puzzle have exactly one solution?
Yes. Every puzzle on this page is generated in your browser and checked to have exactly one solution, so a finished grid is never a guess between two valid answers.
How do I win a game?
Fill every empty cell with the correct digit. When the grid is complete and correct, you win and see your time, mistakes, and hints used. Your best time per difficulty is saved in your browser.