Sudoku
May 21, 2026 — Colorpix
Three new free tools went online recently: a sudoku generator, a sudoku solver and a sudoku for kids. Generate a puzzle to your liking, get a tough sudoku solved step by step, or play a symbol sudoku with the little ones. No account, no ads inside the puzzle, no download limit.
What is sudoku again?
Sudoku is a logic puzzle on a 9×9 grid divided into nine 3×3 blocks. Every row, every column and every block must contain the digits 1 to 9 exactly once. A good sudoku always has exactly one solution and can be solved with pure logic, no guessing required. For younger players there are smaller variants too: 4×4 (digits 1-4) and 6×6 (digits 1-6).
1. Sudoku generator — build a puzzle the way you like it
In the sudoku generator you choose:
- Size: 4×4, 6×6 or classic 9×9
- Difficulty: easy, medium, hard or expert
- Play right in your browser, with timer, undo/redo and notes mode
- Download as PDF: 1 puzzle per page, or 4 puzzles per A4 to save paper
Stuck? The smart hint button doesn't just tell you which digit goes where — it also names the technique (Naked Single, Hidden Single, Naked Pair, Hidden Pair) that gets you there. So you actually learn how to solve, instead of just being handed the answer.
2. Sudoku solver — get your own puzzle solved with explanations
Got a sudoku from a newspaper, book or app you really can't crack? On the sudoku solver you enter the given digits and pick Next step for one cell with an explanation, or Full solution for the complete answer. The solver covers six solving techniques, from the simple Naked Single up to the more advanced X-Wing. Useful when you don't just want the answer but also want to understand why it's the answer.
3. Sudoku for kids — from age 4, with symbols
The sudoku for kids is built for young players from about age 4-5. Key differences with the regular generator:
- Only 4×4 and 6×6, so a puzzle stays doable within a reasonable time
- Symbols instead of digits: choose between animals, fruit, colors, vehicles or weather emoji — kids who can't count yet can still play sudoku
- Two levels: Easy and Hard
- Simple interface: no timer, no notes mode, no complicated buttons
A PDF download is available too — handy for printing a whole set of worksheets for the classroom or a rainy Sunday afternoon.
Which level for which age?
A rough starting point by age:
- Age 4-5 (preschool): 4×4 with animals or fruit, easy
- Age 6-7 (1st grade): 4×4 or 6×6 with symbols, easy
- Age 7-8 (2nd grade): 6×6, easy moving up to hard
- Age 8-9 (3rd grade): 6×6 hard, then move on to the regular generator on easy
Tips to solve faster
- Start by scanning one digit at a time. Pick the 1, for example, and see where it already sits — which rows, columns and blocks still need it?
- Look for "Naked Singles": a cell where only one digit still logically fits.
- Use notes mode to jot candidates small in the top of a cell.
- Don't guess — a good sudoku is always 100% logically solvable. Rule out candidates one by one instead.
- Work blocks AND rows/columns at the same time. Sudoku is a combined puzzle.
Example: what a generated puzzle looks like
A 9×9 sudoku on medium typically starts with around 30 filled cells. The kids or beginner 6×6 looks more compact:
Rows 1 to 6, columns 1 to 6, blocks of 3×2. Digits 1 to 6. About 14 cells already filled on easy, about 9 on hard. Every row, every column and every block contains the digits 1 to 6 once in the solution.
The generator verifies that a puzzle has exactly one valid solution before showing it to you. No puzzle with multiple solutions, no puzzle that can only be cracked by guessing.
Free and available in nine languages
The three tools work without an account and are completely free. They are also available in nine languages across our network — English, Dutch, French, German, Spanish, Italian, Portuguese, Norwegian and Swedish — so the interface and hint explanations stay in the same language.
Practical tip
Not sure which tool you need? Start with a fresh puzzle on the generator. Get stuck and don't want to see the whole answer? Copy your puzzle into the solver and ask for a single step with an explanation — often that's enough to get you going again, without spoiling the whole solution. And for the youngest solvers, the symbol version for kids works from around age four.