Sudoku & Puzzle Generator — Free Online Tool

The Sudoku and Puzzle Generator creates playable Sudoku grids at a range of difficulty levels, each with a unique solution.

The uniqueness constraint is what separates a real Sudoku from an arbitrary partially-filled grid. A properly constructed puzzle has exactly one valid completion, which is what makes pure logical deduction sufficient — you never have to guess between branches. Generating one requires solving the grid backwards from a complete solution, removing clues while verifying at each step that uniqueness still holds, which is why generated puzzles are more reliable than hand-made ones.

Difficulty is not simply the number of clues given, which is the common assumption. It is determined by which solving techniques are required: an easy puzzle can be completed by scanning for cells with only one possibility, while harder grids require chained deductions across multiple units. Two puzzles with an identical clue count can sit at very different difficulties depending on where those clues are placed. The known minimum for a uniquely solvable grid is 17 clues, proven by exhaustive computer search in 2012.

Sudoku involves no arithmetic at all despite using digits — the numbers are just nine distinguishable symbols, and the puzzle would work identically with colours or letters. It is a constraint-satisfaction problem, which is why it appeals to people who dislike mental arithmetic.

Puzzles are generated in your browser and can be played on screen or printed.

Our Sudoku & Puzzle Generator is completely free to use with no signup required. For this tool, processing runs in your browser — your files and data stay on your device and are not uploaded to our servers.

Whether you are a developer, designer, student, or business owner, this tool is designed to save you time and make your workflow more efficient. Bookmark this page to access it whenever you need it — it will always be free.