Play Sudoku online for free
Pick a level and start. The board saves your game in this browser, checks your digits as you go and gives hints that explain what to look for.
Choose Easy, Medium, Hard, Expert or Extreme, tap a cell and enter a digit. Turn on notes to pencil in candidates, use Undo freely, and press Hint when stuck: it names the technique and highlights the cell. Everything is free and needs no account.
How to use the board
- Tap a cell, then a digit. On a keyboard, use 1 to 9, Backspace to erase and the arrow keys to move.
- Turn Notes on to write small candidate digits. Press N on a keyboard.
- Hint finds a naked or hidden single and tells you which one it is.
- Your game is saved in this browser. Nothing is sent anywhere.
How to play
- Choose a level in the menu above the board, or press New puzzle for another one.
- Tap a cell, then tap a digit below the board. On a keyboard, type 1 to 9.
- Fill the grid so every row, column and 3 by 3 box contains 1 to 9 exactly once. New to the rules? Read how to play Sudoku.
- Wrong digits turn red straight away, and the mistake counter goes up. Use Undo to take back a move.
Pick the right level
Levels here follow the techniques a puzzle needs, not just how many digits are given. That keeps each level predictable.
- Easy: only naked and hidden singles. A good place to start.
- Medium: adds pairs, pointing pairs and box-line reduction.
- Hard: needs triples. Notes become essential.
- Expert: X-Wing and Swordfish patterns across the grid.
- Extreme: XY-Wing and coloring. Rewarding, but very demanding.
Use notes like a pro
Notes (also called pencil marks) are small candidate digits in a cell. Writing them makes patterns visible, and every technique on the techniques page relies on them. Placing a digit removes it from the notes of its row, column and box automatically, so you do not have to clean up. Details in the guide to notes.
Hints that explain
The Hint button looks for a naked single or a hidden single and highlights it, with a sentence on why it works. If neither exists, it points you to the cell with the fewest candidates. For harder positions, paste the grid into the step-by-step solver, which names every technique up to XY-Wing.
Your progress stays private
The current game, notes and timer are stored only in this browser. There is no account, and clearing site data starts you fresh. Want puzzles on your phone? The Android app uses the same graded puzzles and works offline.
Frequently asked questions
Is this Sudoku really free?
Yes. There is no sign-up, no paywall and no limit on puzzles.
Does the game save my progress?
Yes, in your browser. Close the tab and come back on the same device to continue the same puzzle.
Are the puzzles unique?
Every puzzle has exactly one solution and can be solved by logic. You never have to guess.
What if I get stuck?
Press Hint, or use the step-by-step solver to see which technique applies next.