Play Free Sudoku Online Puzzles

Challenge your brain with classic Sudoku, mini grids, Killer, Jigsaw, and more — all free, no sign-up required.

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Sudoku Puzzles

Pick a variant and start solving. New puzzles are generated every day.

Classic 9x9 Sudoku grid
Classic

Sudoku

The original 9×9 puzzle. Fill every row, column, and 3×3 box with the digits 1–9. Available in easy, medium, hard, and expert.

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17 clue sudoku grid with a sparse minimum-clue puzzle
Minimum

17 Clue Sudoku

A true minimum-clue challenge. Every classic 9x9 grid starts with exactly 17 givens from the known 17-clue collection.

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Hardest Sudoku Ever grid preview
Legendary

Hardest Sudoku Ever

Play Arto Inkala's famous grid plus two David Filmer challengers often ranked even harder by expert sudoku communities.

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4x4 mini Sudoku grid
Beginner

4×4 Sudoku

A smaller grid using digits 1–4. Perfect for kids and first-time players who want to learn the rules quickly.

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6x6 Sudoku grid
Intermediate

6×6 Sudoku

A medium-sized grid with 2×3 boxes and digits 1–6. Great stepping stone between 4×4 and the full 9×9 puzzle.

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Killer Sudoku grid with cage sums
Advanced

Killer Sudoku

Combines Sudoku with Kakuro. Groups of cells (cages) must sum to a given total — no number can repeat within a cage.

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Jigsaw Sudoku grid with irregular regions
Variant

Jigsaw Sudoku

Replaces the standard 3×3 boxes with irregular jigsaw-shaped regions. Same rules, fresh challenge.

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Samurai Sudoku grid with five overlapping puzzles
Advanced

Samurai Sudoku

Five overlapping 9×9 grids in a cross pattern. The ultimate multi-grid Sudoku challenge.

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X Sudoku grid with highlighted diagonals
Variant

X Sudoku

Classic Sudoku with a diagonal twist. Both main diagonals must also contain 1–9 — an elegant extra constraint.

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Hyper Sudoku grid with four shaded window regions
Variant

Hyper Sudoku

Also known as Windoku. Four extra shaded 3×3 window regions must each contain 1–9 — a visually striking extra challenge.

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Thermo Sudoku grid with thermometer constraints
Variant

Thermo Sudoku

Thermometer lines cross the grid — digits must strictly increase from bulb to tip. A visual and logical twist on classic Sudoku.

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Arrow Sudoku grid with arrow constraints linking circle cells to path cells
Variant

Arrow Sudoku

Arrows connect a circle to a path — digits along the arrow must sum to the circle digit. Arithmetic meets logic!

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Kropki Sudoku grid with black and white dots between cells
Variant

Kropki Sudoku

Black and white dots reveal ratio and consecutive clues between neighbours. No dot means neither — use every absence as a clue!

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Sandwich Sudoku grid with sum clues outside the board
Variant

Sandwich Sudoku

Clue numbers reveal the sum of digits sandwiched between the 1 and 9 in each row and column. A delicious twist on classic logic!

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Anti-Knight Sudoku grid with chess knight constraint
Variant

Anti-Knight Sudoku

Combines Sudoku with chess — no two identical digits can be a knight's move apart. A spatial twist that adds a whole new layer of logic!

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Odd-Even Sudoku grid with parity-shaded cells
Variant

Odd-Even Sudoku

Cells are colour-coded by parity — odd or even. The shading halves your candidates instantly, adding an elegant visual twist to classic Sudoku.

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Battenburg Sudoku grid with checkerboard parity markers
Variant

Battenburg Sudoku

Checkerboard parity markers sit at cell intersections. Where a marker appears, the four surrounding cells must alternate odd and even — like a Battenburg cake.

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Battleship Sudoku grid with ship segments and row column counts
Variant

Battleship Sudoku

A hidden fleet of ships is placed in the grid. Row and column counts reveal how many ship segments appear in each line. Combine Sudoku logic with Battleship placement for a uniquely satisfying challenge.

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Greater Than Sudoku grid with inequality signs between cells
Variant

Greater Than Sudoku

Inequality signs between cells reveal which neighbour is larger. Combine comparison clues with classic Sudoku logic for a unique challenge.

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12x12 Sudoku grid with 3x4 boxes
Advanced

12×12 Sudoku

A giant 12×12 grid with 3×4 boxes and digits 1–12. The ultimate size-up from classic Sudoku — 144 cells of pure logic.

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16x16 Sudoku grid with 4x4 boxes
Advanced

16×16 Sudoku

A massive 16×16 monster grid with 4×4 boxes and digits 1–16. The biggest Sudoku challenge — 256 cells of extreme logic.

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25x25 Sudoku grid with 5x5 boxes
Advanced

25×25 Sudoku

The colossal 25×25 grid with 625 cells, digits 1–25 and twenty-five 5×5 boxes. The largest standard Sudoku — a monumental test of logic.

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Calcudoku grid with coloured arithmetic cages
Variant

Calcudoku

Combine Latin-square logic with arithmetic. Cages show a target number and operation — use addition, subtraction, multiplication and division to solve grids from 4×4 to 9×9.

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NRC Sudoku grid with four shaded window regions
Variant

NRC Sudoku

Named after the Dutch newspaper NRC Handelsblad. Four extra shaded 3×3 window regions must each contain 1–9 — 31 constraint groups in total.

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Skyscraper Sudoku grid with visibility clues around the edges
Variant

Skyscraper Sudoku

Clue numbers around the edges reveal how many skyscrapers are visible from each direction. Taller buildings block shorter ones — a spatial-logic twist on classic Sudoku!

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Letter Sudoku grid with letters A to I
Variant

Letter Sudoku

Swap digits for letters A–I! Same 9×9 logic, fresh alphabetical twist. Also known as Alphabet Sudoku or Wordoku.

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Color Sudoku grid with colourful dots instead of digits
Variant

Color Sudoku

Replace digits with nine vibrant colours! Same Sudoku logic, stunning visual twist. A rainbow of pure deduction.

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Diagonal Sudoku grid with shaded main diagonals
Variant

Diagonal Sudoku

Classic 9×9 Sudoku plus one powerful rule: both main diagonals must also contain 1–9. Simple twist, deeper logic.

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Wordoku grid with letters from a hidden word
Variant

Wordoku

Sudoku meets word games! Fill the 9×9 grid with letters from a hidden nine-letter word. Solve the grid, discover the word.

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8×8 Sudoku grid with 2×4 rectangular boxes
Intermediate

8×8 Sudoku

A unique 8×8 grid divided into 2×4 rectangular boxes. Fill every row, column, and box with the digits 1–8. The perfect bridge between 6×6 and classic 9×9.

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Asterisk Sudoku grid with star-shaped shaded region
Variant

Asterisk Sudoku

Classic 9×9 Sudoku with a star-shaped twist. Nine shaded cells forming an asterisk pattern must also contain 1–9 — an elegant extra constraint.

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Windoku grid with four shaded window regions
Variant

Windoku

Classic 9×9 Sudoku with four extra 3×3 window regions. Each shaded window must also contain 1–9 — 31 constraint groups in total.

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Symbol Sudoku grid filled with shapes instead of numbers
Variant

Symbol Sudoku

Replace digits with nine unique symbols — ★ ♦ ♠ ♥ ♣ ▲ ● ■ ♪. Same 9×9 logic, fresh visual twist that tests pattern recognition.

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Emoji Sudoku grid filled with colourful emojis instead of numbers
Variant

Emoji Sudoku

Replace digits with nine fun emojis — 🌟 🔥 🎵 💎 🌈 🍀 🎯 ⚡ 🦋. Same 9×9 logic, colourful twist that's fun for all ages.

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Renban Sudoku grid with coloured groups of consecutive digits
Variant

Renban Sudoku

Coloured groups must contain consecutive digits — combine sequence logic with classic Sudoku rules.

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German Whispers Sudoku grid with green difference lines
Variant

German Whispers Sudoku

Green lines where adjacent digits must differ by at least 5. High-low alternation logic meets classic Sudoku rules.

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Consecutive Sudoku grid with orange neighbour markers
Variant

Consecutive Sudoku

Orange markers show where adjacent digits differ by exactly 1. Use both the markers and their absence to solve the puzzle.

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XV Sudoku grid with Roman-numeral sum markers between cells
Variant

XV Sudoku

Roman-numeral markers reveal which neighbours sum to 10 (X) or 5 (V). No marker means neither — every gap is a clue.

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Twin Sudoku grid with two overlapping 9×9 grids sharing a 3×3 box
Advanced

Twin Sudoku

Two 9×9 grids side by side, sharing a single 3×3 box. Solve both puzzles at once — every digit in the overlap must satisfy both grids.

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Mirror Sudoku grid with 180° rotational symmetry constraint
Variant

Mirror Sudoku

Every cell and its 180°-rotational partner must sum to 10. One digit placed reveals another — symmetry meets logic in this elegant variant.

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Multiplayer Sudoku grid for two players competing head to head
Variant

Multiplayer Sudoku

Two players, one grid — compete head-to-head in turn-based 1v1 Sudoku. Race against the clock or battle for the highest score.

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Sixy Sudoku 6×6 grid puzzle with digits 1 to 6
Beginner

Sixy Sudoku

A compact 6×6 grid with 2×3 boxes and digits 1–6. Quick, fun, and perfect for beginners and kids.

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Snowflake Sudoku hexagonal board with six hexagons and triangular cells
Variant

Snowflake Sudoku

Six hexagons arranged in a snowflake ring, each with six triangular cells. Fill every hexagon and line with 1–6.

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Circle Sudoku circular grid with concentric rings and wedge sectors
Variant

Circle Sudoku

A circular grid of concentric rings and wedge sectors. Fill every ring, sector, and arc box with the digits 1–6.

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Shape Sudoku grid with geometric shapes instead of digits
Variant

Shape Sudoku

Nine geometric shapes replace the digits 1–9. Same 9×9 logic, fresh visual twist — perfect for all ages.

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Alphabet Sudoku grid with random letters from A to Z
Variant

Alphabet Sudoku

Nine random letters from the full A–Z alphabet every game. Same 9×9 logic, a fresh set of letters each time.

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Sudoku dark mode 9x9 grid
Dark Mode

Sudoku Dark Mode

Play classic 9×9 Sudoku in a low-glare dark theme. The sun/moon toggle lets you switch all our Sudoku games between light and dark mode.

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Why Play Sudoku Here?

Everything you need for a great sudoku experience, all in one place.

100% Free

No subscriptions, no paywalls, no sign-ups. Just pick a puzzle and play instantly.

Notes & Pencil Marks

Toggle pencil mode to jot candidates in every cell — just like solving on paper.

Timer & Stats

Track your solve times and watch your skills improve over days, weeks, and months.

Hints When You're Stuck

Smart hints explain the next logical step so you can learn while you play.

More Sudoku Resources

Printable puzzles, an automated solver, and articles to sharpen your game.

Printable Sudoku

Download and print puzzles in easy, medium, hard and expert — great for offline play.

Sudoku Solver

Paste or type your puzzle and get an instant solution with step-by-step logic.

Blog & Sudoku Tips

Strategies, techniques, and beginner guides to help you solve puzzles faster.

The Ultimate Destination for Sudoku Online Puzzles

Whether you're a complete beginner or a seasoned solver, Sudoku Online Puzzles has something for everyone. Our growing library features classic 9×9 grids, smaller 4×4 and 6×6 boards for newcomers, and challenging variants like Killer Sudoku and Jigsaw Sudoku for advanced players.

How to Play Sudoku

Sudoku is a logic puzzle played on a grid divided into rows, columns, and smaller boxes. The goal is simple: fill every empty cell so that each row, column, and box contains each digit exactly once. No guessing is needed — every puzzle can be solved through pure deduction.

Sudoku Puzzles for Every Skill Level

Not sure where to start? Try our easy sudoku puzzles — they use more given digits so you can build confidence. Ready for more? Step up to medium, hard, or even expert grids that require advanced techniques like X-Wing, Swordfish, and naked pairs.

  • Easy & Beginner Sudoku — Learn the basics with plenty of clues.
  • Medium Sudoku — The sweet spot for daily practice.
  • Hard & Expert Sudoku — Test your logic with fewer starting digits.
  • Kids Sudoku (4×4 & 6×6) — Smaller grids that are fun for younger solvers.

Play Anytime, Anywhere

Our puzzles work seamlessly on desktop, tablet, and mobile. Pick up where you left off with auto-save, or download a printable PDF for your commute. New puzzles are generated every day so you'll never run out of challenges.

Frequently Asked Questions

Quick answers to common sudoku questions.

Sudoku is a logic-based number puzzle where you fill a 9×9 grid so that every row, column, and 3×3 box contains the digits 1 to 9 exactly once. No maths is required — just logic and deduction.

Yes! Every sudoku puzzle on Sudoku Online Puzzles is 100% free to play. No sign-up needed — just pick a game and start solving.

We offer classic 9×9 Sudoku, beginner-friendly 4×4 and 6×6 grids, Killer Sudoku (with cage sums), and Jigsaw Sudoku (with irregular regions). More variants are added regularly.

Absolutely. Visit our Printable Sudoku section to download and print puzzles in easy, medium, and hard difficulties — perfect for offline solving.

Enter your partially filled grid into our Sudoku Solver and it will find the solution instantly. It's a great learning tool — you can also step through the logic to understand each move.