Play Free Sudoku Online

Game mode: Classic Sudoku Killer Sudoku
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.

Tap to enter · press and hold to add a NotePress 1–9 to enter · Shift + number for quick Pencil marks
Sound & controls Save on this device

Auto candidates and Notes mode are remembered separately for Classic and Killer. Pause state and game progress are not synced as preferences.

Train your brain

Improves logic, memory, and concentration.

Reduce stress

Helps you relax and reduce stress.

Completely free

Unlimited play, no registration required.

Track progress

Detailed statistics and achievement tracking.

What is Classic Sudoku?

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

Play Sudoku Online by Difficulty

See how to choose a level

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

Sudoku solving guide cluster

How to Solve Sudoku

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. Naked Single Sudoku – Find Forced Cells Fast Learn how to spot a Naked Single in Sudoku, verify the only candidate left in a cell, and turn forced cells into a reliable solving loop. Hidden Single Sudoku – Find the Only Place Learn Hidden Singles in Sudoku: track one digit across a row, column, or box, find its only legal position, and avoid confusing them with Naked Singles. Sudoku Candidates & Pencil Marks – Practical Guide Use Sudoku candidates and pencil marks accurately: calculate legal digits, keep notes updated, and prepare for Locked Candidates, Pairs, and X-Wing. 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.
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