Sudoku
Fill the grid so that every row, column and 3×3 box contains the digits 1 to 9 exactly once. Each puzzle is generated in your browser, has a single solution and is rated by the techniques it needs.
How to use it
- Choose a level and tap New game.
- Tap a cell and a digit; turn on Notes to write small candidates.
- Use Hint or Show mistakes if you get stuck; the game is saved in this browser.
Frequently asked questions
How are the levels chosen?
By the techniques a person needs: easy puzzles fall to cells with a single candidate, medium ones also need the only place for a digit in a row, column or box, hard ones need pairs and box-line eliminations, and expert ones need more.
Does every puzzle have one solution?
Yes. Each clue is removed only if the puzzle still has exactly one solution, checked by a complete solver, so it can always be solved by logic without guessing.
Can I use the keyboard?
Yes: arrows move between cells, digits 1–9 fill in, N switches notes, Backspace or Delete erases and Ctrl+Z undoes.