Mondo Knows Puzzles
Free sudoku online
The classic number placement puzzle. Every row, every column and every 3x3 box must contain the digits 1 to 9 exactly once. Mondo generates each grid fresh and guarantees it has exactly one solution. There is no daily limit and no account: ask for a new grid whenever you finish one, and your best time is remembered on this device.
Drawing the grid…
How to play
- Click a square to select it.
- Use the number pad or your keyboard to place a digit.
- A square that clashes with another is marked red.
- Use Hint if you are stuck and Check to look for mistakes.
Questions people ask
- Is this sudoku free, and does it need an account?
- Free, with no account. The grid is generated and solved in your browser, so it works offline once the page has loaded and nothing you enter is stored on a server.
- What do the difficulty levels change?
- Easy grids can be finished with simple scanning, medium grids need you to pencil in candidates, and hard grids need advanced techniques. Every grid is checked to have exactly one solution before it is dealt.
- What do the hint and check buttons do?
- The check button marks entries that break sudoku's three rules: a digit repeated in a row, a column or a 3x3 box. The hint button reveals one cell from the solved grid, so you can always make progress.