Play Sudoku Online for Free
Minimal. Focused. Precise.
Free online Sudoku in four levels: Easy, Medium, Hard and Expert. Unlimited puzzles, no registration and a clean, distraction-free board. New to the game? Learn how to play Sudoku.
Your Sudoku Stats & Achievements
Every finished puzzle adds to your win rate, streaks and best times, and can unlock achievements. It is all saved privately in this browser, with no account.
Solve your first puzzle to start your stats. Your best times, streaks and achievements will appear here.
Personal Best Times
Your fastest solve per difficulty. Best streak so far: 0.
Achievements
0 / 20 unlocked
Try Today's Daily Sudoku
One shared Medium puzzle every day, the same grid for every player. Solve it to start a daily streak and see how long you can keep it going.
An Online Sudoku Game Built for Focus
intosudoku is a free online Sudoku game with the tools of a serious Sudoku app and none of the clutter: no pop-ups mid-game, no forced account, no distractions on the grid.
Instant Play, No Registration
Open the page and start a puzzle in seconds. There is no account to create and no app to install: it runs in any browser on desktop, tablet and mobile.
Pencil Notes
Switch on notes mode to keep track of the numbers a cell could still be, just like pencilling in a paper puzzle book. Notes clear themselves as you place numbers. Learn how to use notes on hard puzzles.
Undo Any Mistake
Take back any move, as many times as you need. Test an idea, and step back if it leads nowhere.
Hints When You're Stuck
Each game gives you three hints. A hint reveals one correct cell, so you get unstuck without spoiling the rest of the puzzle.
Autosave & Resume
Your grid, notes and timer save automatically after every move. Close the tab mid-puzzle and pick your game up exactly where you left off.
Personal Stats & Best Times
Track your fastest solve per difficulty, win rate, streaks and achievements, kept on your device. See them right under the game or on your Sudoku stats page.
Sudoku Puzzles for Every Skill Level
Choose easy, medium, hard or expert Sudoku puzzles. Every online Sudoku grid is generated in your browser with exactly one solution, so logic is always enough. Difficulty depends on the techniques a puzzle needs, not only on how many numbers are given. Not sure where to start? See which difficulty suits you.
Start Playing Sudoku in Three Steps
Choose a difficulty
Select Easy, Medium, Hard or Expert and press Start Puzzle. A new Sudoku grid is generated instantly.
Fill in the grid
Select a cell and enter a number, or switch to notes mode to mark candidates. Matching numbers highlight across the board.
Solve or save for later
Finish in one sitting to record your time, or close the tab. Your puzzle is saved, and you can continue it when you return.
How to Play Sudoku
A Sudoku puzzle is a 9×9 grid split into nine 3×3 boxes. Some numbers are given at the start. Fill in the empty cells using the digits 1 to 9 so that three simple rules are always true. Want the full walkthrough? Read our complete guide to how to play Sudoku.
One of each per row
Each horizontal row must contain every digit from 1 to 9 exactly once.
One of each per column
Each vertical column must also contain every digit from 1 to 9 exactly once.
One of each per box
Each 3×3 box must contain every digit from 1 to 9 exactly once. No number can repeat inside a box.
Sudoku Strategies for Beginners
You never need to guess. These techniques will solve every easy and medium puzzle, and most hard ones. Go deeper with our full list of Sudoku strategies.
Scan for the obvious
Pick a digit and check every box for it. If rows and columns already block all but one cell in a box, that digit must go there.
Find naked singles
Look at one empty cell and rule out every digit already in its row, column and box. If only one number is left, fill it in.
Find hidden singles
Sometimes a digit fits in only one cell of a row, column or box, even if that cell has other candidates. That cell is the answer.
Use pencil notes
On hard and expert Sudoku, note every candidate in each cell. Patterns become visible that you can't hold in your head.
Spot naked pairs
If two cells in the same unit can only be the same two digits, remove those digits from every other cell in that unit.
Update after every move
Each number you place removes candidates in its row, column and box. Recheck those cells first; new singles often appear there.
Sudoku FAQ
What is Sudoku?
Sudoku is a logic-based number puzzle played on a 9×9 grid divided into nine 3×3 boxes. Some cells start filled in, and your goal is to complete the grid so every row, column and box contains the digits 1 to 9 exactly once. No math is needed, only reasoning. Read the full Sudoku rules.
Can I play Sudoku online for free?
Yes. Every puzzle on intosudoku is free to play at all four difficulty levels: Easy, Medium, Hard and Expert. There is no subscription, no paywall and no limit on how many puzzles you can play.
Do I need an account to play?
No. There is no registration, login or password. Open the page and start playing. Your best times, win rate, streaks and achievements are saved locally in your browser, and you can optionally add a display name on the stats page.
Can I play Sudoku on my phone?
Yes. intosudoku works in any modern browser on phones, tablets and computers, and the board and number pad resize to fit small screens. There is no app to download. Open the site and start playing.
How do I choose the right difficulty?
Start with Easy if you are new to Sudoku. Move up to Medium once you can finish Easy puzzles without hints, then try Hard and Expert. Harder levels start with fewer given numbers and usually call for more advanced techniques such as pencil notes, hidden singles and pairs. Read our guide on how to play Sudoku to learn them.
Can I save my progress and continue later?
Yes. Your board, pencil notes, timer, hints and mistake count are saved automatically in your browser after every move. Come back on the same device and browser and you will see a Continue Your Game prompt with your puzzle exactly as you left it. Clearing your browser data removes the save.
What happens when I complete a puzzle?
You see your solve time, mistakes and hints used, and the result is added to your personal stats: best time per difficulty, win rate and winning streak. You may also unlock an achievement. From there you can play another puzzle, change the difficulty, view your stats or challenge a friend with the same puzzle.
Does every puzzle have a unique solution?
Yes. Every intosudoku puzzle is checked to have exactly one valid solution, so it can always be solved with logic alone. No guessing is required.
Your Next Sudoku Puzzle Is Waiting
Pick a difficulty and play Sudoku online right now, completely free. No download, no registration.