Play Sudoku Online for Free
Sudoku Online is a free sudoku generator and printable puzzle maker at sudoku-puzzles.online. Play 3×3 to 9×9 sudoku right in your browser, or switch to the printable page to design custom themed templates. No signup, no download, unlimited puzzles.
About Sudoku Online
Sudoku is a logic puzzle played on a grid divided into boxes. The goal is to fill every cell with a digit so that each row, column and box contains every digit exactly once. Sudoku Online generates puzzles with a unique solution, so you never have to guess.
Our generator supports seven grid sizes: 3×3, 4×4 and 6×6 for young children, 5×5, 7×7 and 8×8 as intermediate variants, and standard 9×9 sudoku. Every puzzle can be played online with hints, timer and instant checking, or printed from the printable sudoku page.
New to sudoku? Read the how to play guide for rules and beginner strategies.
Printable Sudoku — Custom Themes & Templates
Design and print your own sudoku templates. Choose a grid size, difficulty, color theme and cartoon style, then export a single puzzle or a batch of random puzzles with their solutions. Every printable page is generated fresh with a unique solution, free and ready to print.
What you can customize
- Grid size — 3×3, 4×4, 5×5, 6×6, 7×7, 8×8 or 9×9 sudoku
- Difficulty — Easy, Medium, Hard or Evil
- Color theme — Classic, Indigo, Emerald, Sunset and more
- Cartoon theme — Candy, Forest, Space, Sakura, Dino and more, with adjustable decoration density
- Background image — upload your own image for a fully custom template
- Batch export — print 3, 4 or 5 random puzzles, each with its own theme and matching answer page
How to print
- Pick a grid size and difficulty.
- Choose a color theme or cartoon theme.
- Click Free Export Puzzle to print one puzzle, or use Batch Export to print multiple puzzles with solutions.
- In the browser print dialog, make sure "Background graphics" is enabled, then save as PDF or print directly.
Frequently asked questions
Is printable sudoku free?
Yes, everything on this page is free. No signup, no email, no paywall.
Can I print multiple puzzles at once?
Yes. Choose the 3×3, 4×4 or 5×5 batch option to print 3, 4 or 5 random puzzles, each with its matching answer page.
Can I use my own images?
Yes, upload a background image and it will appear on both the template and inside the grid.
Sudoku Rules & How to Play
Learn the basic sudoku rules and simple beginner strategies. Everything you need to start solving your first puzzle.
The basic rules
Sudoku is played on a grid divided into boxes. The goal is to fill every empty cell with a digit. There are three rules:
- Each row must contain every digit exactly once.
- Each column must contain every digit exactly once.
- Each box must contain every digit exactly once.
A quick example
Suppose a 9×9 row already contains 1, 2, 3, 5, 6, 7, 8 and 9. The only missing digit is 4, so the empty cell in that row must be 4.
The empty cell = 4
Grid sizes
- 3×3 — digits 1–3, one row per box. Easiest possible puzzle.
- 4×4 — digits 1–4, with 2×2 boxes.
- 5×5 — digits 1–5, Latin-square style.
- 6×6 — digits 1–6, with 2×3 boxes.
- 7×7 — digits 1–7, Latin-square style.
- 8×8 — digits 1–8, with 2×4 boxes.
- 9×9 — the classic standard sudoku.
Beginner strategies
Scan rows and columns
Pick a number and scan the grid. In every box, ask: where can this number go? Use existing digits in rows and columns to eliminate cells.
Use the box rule
Inside a box, if all cells but one are filled, the last cell must be the missing digit. This is the simplest way to make progress.
Pencil in candidates
For harder puzzles, write small candidate numbers in each empty cell. When a cell has only one candidate left, that's the answer.
Look for naked singles
A "naked single" is a cell where only one digit can possibly go. Scan every empty cell and check which digits are already used in its row, column and box. If only one digit remains, that's the answer.
Practice with easy puzzles
Start with an easy puzzle to build confidence. When you can solve easy puzzles reliably, move up to medium and hard.
What makes a valid puzzle
A well-formed sudoku has exactly one solution. Every puzzle on this site is verified to have a unique solution before it is generated, so you never have to guess.
Ready to play?
Start with an online sudoku on the home page, or browse the printable sudoku page to design your own template.
About Sudoku Online
Sudoku Online is a free sudoku generator and printable puzzle maker at sudoku-puzzles.online. It was built for players, teachers, parents and anyone who enjoys a good logic puzzle.
What we offer
- Online sudoku — play 3×3 to 9×9 puzzles directly in your browser, with timer, pause, hints and instant checking.
- Printable sudoku — design custom templates with color themes, cartoon decorations and background images, then print or export as PDF.
- Batch export — generate 3, 4 or 5 random puzzles at once, each with its own theme and matching answer page. Perfect for classrooms and activity sheets.
- Beginner guides — clear rules and step-by-step strategies for new players.
Our principles
- Always free — no signup, no email, no paywall.
- Unique solutions — every puzzle is verified to have exactly one solution.
- No tracking — we don't sell your data.
- Kid-friendly — smaller grids and cartoon themes for younger players.
How puzzles are generated
Every puzzle is generated in your browser using a backtracking algorithm. The generator first fills a complete valid grid, then removes clues one by one while checking that the puzzle still has a unique solution. This guarantees that every puzzle you play or print is solvable by logic alone.
Contact us
Questions, feedback or bug reports are welcome. We usually reply within a few days.
General inquiries: hello@sudoku-puzzles.online
Bug reports: support@sudoku-puzzles.online
Business & partnerships: business@sudoku-puzzles.online
Privacy
Sudoku Online runs entirely in your browser. Puzzle data and guestbook messages are stored locally on your device (localStorage) and are never uploaded to a server.