Click a cell, then a number 1–9. Keyboard: arrows to move, 1–9 to fill, Backspace to erase.
About sudoku
Free sudoku online — the classic 9×9 number puzzle, no signup or installation required. Fill the grid so every row, every column, and every 3×3 box contains the digits 1–9 exactly once. Four difficulty levels cover newcomers through experts, with a running solve timer if you want to race yourself.
Mistakes are highlighted but never punished — undo and try again whenever. Pondernook sudoku is designed for clean five-to-fifteen minute sessions in any browser; pencil-mark notes are supported. Hard puzzles include techniques like hidden pairs and X-wings; easy puzzles solve with naked singles alone. No daily-streak pressure, no ads in your peripheral vision — just the puzzle and the keyboard.