Sudoku Generator

About Sudoku Generator

The most complete free online Sudoku generator. Creates valid 9×9 Sudoku puzzles using a backtracking algorithm with unique solution guarantee for Hard, Expert, and Evil difficulties. Play interactively with keyboard support (arrow keys + number keys), pencil marks (candidate notation), smart hints, undo/redo, mistake tracking, and a built-in timer. Export puzzles as high-resolution PNG images or open a printer-friendly page for paper solving. Features 5 difficulty levels from Easy (42 clues) to Evil (20 clues), a number pad with remaining digit counts, cell highlighting for related rows/columns/boxes, and completion detection. No sign-up required — runs entirely client-side.

Sudoku Generator Features

• 5 difficulty levels: Easy (42 clues), Medium (33), Hard (27), Expert (23), Evil (20)
• Unique solution guarantee for Hard, Expert, and Evil puzzles via constraint checking
• Interactive play mode with cell selection, keyboard input, and arrow key navigation
• Pencil marks (candidate notation) — toggle candidates per cell for advanced solving
• Smart hint system that reveals one random empty cell from the solution
• Undo history — step back through every move you've made
• Built-in timer with automatic stop on puzzle completion
• Mistake counter — errors highlighted in red with running total
• Number pad with remaining digit counts (shows how many of each number are left)
• Related cell highlighting — row, column, and 3×3 box highlight on selection
• High-resolution PNG export via Canvas API with difficulty label
• Print-ready HTML — opens a clean printable page for paper solving
• Copy puzzle as text (dots for empty cells) for sharing
• Completion detection with celebration banner and stats summary
• Premium dark sidebar layout with GSAP animations and Aceternity components