How to play
- Fill the 9 × 9 grid so that every row, every column, and every 3 × 3 box contains the digits 1–9 exactly once.
- Click a cell to select it, then type a digit (1–9) or use the on-screen number pad. Press 0 or Backspace to clear.
- Toggle Notes mode (or press N) to add small candidate marks to a cell. Tap a candidate again to remove it.
- Use arrow keys to move between cells. Hint places one correct digit; Check highlights any current mistakes; Undo reverses your last move.
Daily Sudoku
The "Daily" puzzle is generated deterministically from today's UTC date, so every player worldwide gets the same Daily Sudoku for that day. Switch to "Random" for an unlimited stream of fresh puzzles.
Difficulty levels
- Easy — about 40–42 clues. Solvable mostly by spotting hidden singles and obvious placements.
- Medium — about 34–36 clues. Some scanning and pencil-mark logic required.
- Hard — about 30–32 clues. Locked candidates and pointing pairs help.
- Expert — about 26–28 clues. Patient pencil-mark reasoning plus advanced techniques.
FAQ
Are the puzzles unique?
Yes — each puzzle is generated and verified to have exactly one solution before being shown.
Does my progress save if I refresh?
Your current board state is auto-saved to your browser as you play, so a refresh won't lose your progress on the current puzzle.
Can I print a puzzle?
Yes — use your browser's print function (Ctrl/Cmd + P). The board and current pencil marks will print on a clean page.