Sudoku
Freshly generated puzzles at four difficulties, with hints and mistake checking.
Play Sudoku with a fresh, uniquely-solvable puzzle generated every time — choose Beginner, Intermediate, Advanced, or Expert, get a hint when stuck, and check your work as you go. Works full-screen on mobile.
Frequently asked questions
Is every puzzle guaranteed to have exactly one solution?
Yes — each puzzle is generated fresh and verified to have a unique solution before it's shown to you, using the same technique real Sudoku puzzle generators use. It's never ambiguous or unsolvable.
What do the board sizes mean?
9 Box is the classic 9×9 Sudoku with digits 1-9 and nine 3×3 boxes. 4 Box is a 6×6 version with digits 1-6, using six 2×3 boxes — a gentler way to learn the rules. 1 Box is a 3×3 mini-puzzle with just digits 1-3 and no separate box rule (rows and columns already cover the whole grid), good for very young kids or a quick warm-up.
How are the difficulty levels different?
Difficulty is based on how many starting numbers ("clues") the puzzle has relative to the board size — fewer clues means more deduction is needed. It's a reasonable approximation rather than an exact science, especially on the smaller boards where there's less room to vary.
What does Hint do?
It fills in the correct number for your currently selected empty cell — or a random empty cell if none is selected — using the puzzle's known solution.
What does Check do?
It highlights any cells you've filled in that don't match the puzzle's solution, without revealing what the correct number actually is.
Is my progress uploaded anywhere?
No — the puzzle is generated and solved entirely in your browser using plain JavaScript. Nothing is sent to a server.