Train your brain
Improves logic, memory, and concentration.
Play Free Sudoku Online
Difficulty
Error
0 / 3
Time
00:00
Score
1.400
9×9 Sudoku board. Use the arrow keys to move between cells; Home and End go to the start or end of a row; Ctrl or Command + Home/End goes to the first/last cell on the board. Keys 1–9 enter a digit in the current mode; Shift + 1–9 adds a quick Note without turning Notes on; 0, Delete, or the numpad decimal key clears a cell; N toggles Notes, A toggles Auto Candidates, and Space pauses the game.
Smart hints
Classic Sudoku · 3 levels
1–3
Levels 1–2 only guide you and do not use a hint; level 3 applies the solving step and uses 1 hint.
Tap to enter · press and hold to add a NotePress 1–9 to enter · Shift + number for quick Pencil marks
Select an empty cell to see valid candidates.
Sound & controls
Auto candidates and Notes mode are remembered separately for Classic and Killer. Pause state and game progress are not synced as preferences.
Reduce stress
Helps you relax and reduce stress.
Completely free
Unlimited play, no registration required.
Track progress
Detailed statistics and achievement tracking.
Play Sudoku Online for Free
Sudoku online is the classic 9×9 logic puzzle. Fill the empty cells with digits 1 through 9 so every row, column, and 3×3 block contains each digit once.
Play unlimited Sudoku online across six difficulty levels from Easy to Extreme. Use notes, hints and logical elimination to solve systematically without guessing.
See how to play Sudoku step by step
Choose by skill level
See how to choose a level
Play Sudoku Online by Difficulty
Start at a level that is challenging enough while still letting you find certain moves. Each landing page below has its own solving tips and practice path, from Easy Sudoku for beginners to Extreme Sudoku for experienced players.
Easy Sudoku Online
Naked singles, hidden singles in a row/column/block
Medium Sudoku Online
Candidates, simple pairs, intersection eliminations
Hard Sudoku Online
Hidden pairs, naked pairs, block-row/column intersections
Expert Sudoku Online
Triples, basic X-Wing, elimination chains
Master Sudoku Online
Advanced candidate patterns and multi-step deductions
Extreme Sudoku Online
Combine several advanced patterns while avoiding all random guessing
Learn by technique
How to Solve Sudoku
Sudoku solving guide cluster
Each guide below targets a distinct search intent and skill, from a beginner workflow to locked candidates, pairs, and X-Wing. Follow them in order if you are unsure where to start.
How to solve Sudoku: techniques from basic to advanced
A systematic Sudoku solving path: scan singles, manage candidates, use pairs, locked candidates, and advanced patterns without guessing.
Sudoku Tips for Beginners: Solve Faster with Fewer Mistakes
Practical Sudoku tips for beginners: scan regions, choose good starting points, use Notes at the right time, and avoid habits that make easy games confusing.
Locked Candidates in Sudoku: Pointing & Claiming Explained
Understand locked candidates in Sudoku through pointing and claiming, how to identify the pattern, eliminate candidates in the right places, and avoid common mistakes.
Naked & hidden pairs in Sudoku: how to identify and eliminate digits
Learn the difference between naked and hidden pairs in Sudoku, how to use two candidates for safe eliminations, and the signs that make pairs easier to spot.
What Is X-Wing in Sudoku? How to Spot and Use It Correctly
A step-by-step X-Wing Sudoku guide: four-corner conditions, row/column scanning, candidate elimination, and patterns that are easy to misread.