Sudoku Generator
Generate, solve and print Sudoku puzzles instantly.
What is it?
Our Sudoku Generator creates valid, unique 9×9 Sudoku puzzles at four difficulty levels — Easy, Medium, Hard, and Expert. Each puzzle is generated algorithmically in your browser using a backtracking solver, guaranteeing exactly one solution. You can solve the puzzle right on screen with real-time error highlighting, request a hint, auto-solve it in one click, or print a clean black-and-white version perfect for paper.
How to use it
- Select a difficulty level: Easy, Medium, Hard, or Expert.
- Click "Generate" to create a fresh puzzle.
- Click any empty cell and type a number 1–9 to fill it in.
- Wrong entries are highlighted in red automatically.
- Use "Hint" to reveal one correct cell, or "Solve" to complete the puzzle.
- Click "Print" to open a print-ready layout for paper solving.
Why use this tool
Sudoku is one of the world's most popular logic puzzles, proven to sharpen concentration, working memory, and pattern-recognition skills. Our generator produces an endless supply of fresh puzzles without ads, subscriptions, or app downloads. The in-browser solver means you can check your progress any time, and the print feature lets you take it offline. Whether you are a daily Sudoku player warming up or a teacher creating classroom worksheets, this tool handles it all in seconds.
Frequently asked questions
Does every puzzle have a unique solution?
Yes. The generator uses a constraint-based backtracking algorithm that verifies a single solution before presenting the puzzle.
What is the difference between difficulty levels?
Difficulty is determined by how many cells are pre-filled (givens). Easy: ~36 givens; Medium: ~30; Hard: ~25; Expert: ~22 or fewer, requiring advanced techniques like X-Wings.
Can I print multiple puzzles at once?
Currently the tool prints the active puzzle. Generate a new puzzle, print, repeat — or use browser print-to-PDF to save several.
Does the tool work offline?
Once the page loads, the generator runs entirely in JavaScript with no server calls, so it works even if you lose internet.
Is my progress saved if I close the tab?
Yes, the current puzzle state is saved in your browser's localStorage and restored on your next visit.