Play Hard Sudoku Online — Free 9×9 Puzzles
Start a new Hard Sudoku puzzle instantly. Use hints and pencil marks to solve at your own pace.
Hard Sudoku puzzles give fewer or more starting clues depending on the level. Easy grids are great for learning the rules; expert grids need advanced techniques like naked and hidden singles.
Tips for Hard Sudoku
- Scan rows, columns, and boxes for digits that can only go in one cell.
- Use pencil marks (notes) when more than one candidate remains.
- If you get stuck, take a hint in the free online player — then try the same idea on the next puzzle.
FAQ
What makes a Sudoku Hard?
Difficulty is based on how many clues are given and which solving techniques you typically need. Hard puzzles on Sudoku Guru are generated for a fair, unique solution.
Can I play Hard Sudoku for free?
Yes. Open the player instantly in your browser — no download or account required. Hints and notes are included.