Play free classic Sudoku online. This board uses only rows, columns, and 3×3 boxes, from easy through master, with notes, undo, and hints. Killer cages live in Hell Mode.
This page opens a classic 9×9 Sudoku puzzle in your browser. Select a cell, enter a digit from 1–9, and keep every row, column, and 3×3 box unique. Use notes for candidates, undo to reverse a move, and hints when you want a gentle nudge.
Easy grids start with more givens so beginners can learn scanning. Medium and Hard remove clues and introduce longer logic chains. Expert and Master leave fewer anchors, so pencil marks and structured elimination matter more.
Notes store candidate digits inside a cell. Undo walks back recent moves without restarting. Hints reveal a logical next step when you are stuck. You can also open Print to take the current style of puzzle onto paper.
Find the row, column, or box with the most digits already filled. If only one cell is empty, that digit is forced. If a digit is missing from a box and only one cell in that box does not already see it, you have a hidden single. Practice that scan on Easy, then take the same habit to Medium and Hard.
No. This page is classic Sudoku: each row, column, and 3×3 box contains 1–9 once. Hell Mode adds Killer cages with sum clues. The buttons look similar; the clues do not.
New Game builds another grid at the difficulty you selected. The daily puzzle is separate and stays the same for everyone on that date.
Open Printable Sudoku for PDF worksheets, including large print, kids, and classroom layouts. Printing does not reveal the board you are solving here.