Sudoku
Fill the grid so that every row, every column, and every 3 × 3 box contains the digits 1 to 9 exactly once. Every puzzle is freshly generated and has exactly one solution.
Click or tap a square, then a number. 1–9 enter a digit, 0 or Backspace erases, the arrow keys move, N switches to pencil notes, and Ctrl+Z undoes. Placing a digit clears it from the notes in its row, column, and box. Your puzzle is saved in this browser.