Web apps / Games
Sudoku
Fill every row, column, and 3×3 box with the digits 1 to 9. Every puzzle has exactly one solution.
How to play
Pick a cell, then tap a number. Given numbers can't be changed. A red number doesn't match the solution. The small number on each key shows how many of that digit are still missing.
Turn on Notes to pencil in candidates. When you place a correct number, matching notes in the same row, column, and box are cleared for you. Your game is saved in this browser, so you can close the tab and come back later.
Keyboard: arrow keys to move, 1–9 to fill, Backspace or 0 to erase, N for notes, Ctrl+Z to undo.