Sudoku is the world's favorite logic puzzle, and this free online version gives you unlimited puzzles with everything you need to solve them. Fill the 9x9 grid so that every row, every column and every 3x3 box contains the digits 1 through 9 exactly once. No math is involved, only logic and attention. Choose from easy puzzles that take a few minutes to expert grids that demand advanced techniques like X-Wings and Swordfish. Pencil marks, auto-check, hints and undo make it beginner-friendly, while timers and a daily challenge leaderboard give experienced solvers something to chase. Play Sudoku free in your browser with no download, no app and no account. Your progress saves automatically so you can finish a puzzle later on any device.

How to Play Sudoku

1. The grid starts with some numbers already filled in. These are the givens.
2. Place digits 1 to 9 in the empty cells so no digit repeats in any row, column or 3x3 box.
3. Start with the cells that have only one possible value.
4. Use pencil marks to note candidate numbers in cells with several options.
5. Eliminate candidates row by row, column by column and box by box until every cell is solved.
6. The puzzle is complete when the grid is full and every constraint is satisfied.

Game Modes and Features

• Unlimited puzzles at easy, medium, hard and expert difficulty
• Daily Sudoku challenge with global leaderboard
• Pencil marks and candidate notes
• Hints, mistake highlighting and undo
• Timer with best-time tracking per difficulty
• Auto-save so you can resume any puzzle
• Keyboard input on desktop, tap input on mobile
• Clean, distraction-free interface with dark mode

Sudoku Solving Tips

• Scan for naked singles first: cells where only one number can go.
• Use cross-hatching: check each 3x3 box for where a specific digit must land.
• Look for naked pairs. Two cells in a unit sharing the same two candidates eliminate those numbers elsewhere.
• Never guess. Every valid Sudoku can be solved by logic alone.
• On hard puzzles, learn X-Wing and Swordfish patterns to break through stuck positions.