Online sudoku
Play free online sudoku at easy, medium and hard levels, with a new puzzle every game, error checking, hints and a timer.
How to useFree online sudoku
Available in: 
Online sudoku: what it is for
Each game generates a new sudoku with a unique solution. Choose the level, tap a cell and fill it in with the on-screen keypad or your keyboard. Cells in the same row, column and box are highlighted, and the Check, Hint and Solve buttons help when you get stuck. It works on phones and computers, with no sign-up.
How to use
- Choose the level.
- Tap a cell and choose the number.
- Complete the grid without repeating numbers.
When to use it
- Exercising logical thinking.
- Passing the time on a break.
- Training your concentration every day.
Frequently asked questions
How do you play sudoku?
Fill the 9 × 9 grid with the numbers 1 to 9 so that every row, every column and every 3 × 3 box contains all the numbers, with no repeats. The numbers already in the grid cannot be changed.
Do the puzzles have a unique solution?
Yes. Each sudoku is generated on the spot and the tool only removes numbers while the solution remains unique.
How do I play on a phone?
Tap a cell and then the number on the keypad below the grid. Use the Erase button to clear the cell.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.