About this tool
Sudoku online lets you play a fresh 9×9 puzzle in your browser whenever you like.
The goal is to fill every empty square with 1 to 9 so that each row, each column and each 3×3 box contains every digit exactly once.
Each new puzzle is built on the spot by a backtracking solver that removes numbers one by one and checks that exactly one solution remains, so you never have to guess. How do I choose a difficulty?
Easy leaves 40 starting numbers, Normal 32 and Hard about 26; fewer clues usually means you need more notes and more careful elimination. How do I use the notes?
Turn Notes on, tap a square and tap digits to pencil in candidates; when you place a number, matching notes in its row, column and box are cleared for you.
Numbers that clash with another in the same row, column or box turn red, and the Mistakes counter counts every entry that differs from the solution. Stuck?
A hint fills one correct square, and the number of hints is shown next to your time so you can try for a hint-free run. Example strategy: scan for a digit that has only one legal square in a box, place it, then repeat.
Select a square and tap the number pad on a phone, or use the keyboard digits and arrow keys on a computer. Puzzles are created in your browser, nothing is sent anywhere.
Warm up first with the Daily Color Guessing Game or take a break with Minesweeper Online.
How to use
- Pick Easy, Normal or Hard.
- Tap an empty square, then tap a number on the pad (turn Notes on to pencil in candidates).
- Fix red squares, use Hint if you are stuck, and share your time when the grid is complete.