Free online sudoku: Sudoku Zen
Sudoku Zen is a free online sudoku you can play in your browser, on your phone or on your computer, with nothing to download and no sign-up. Clean, easy-to-read boards, light and dark mode, calm music and a fresh sudoku every time: the generator creates puzzles with a single solution and rates their difficulty by the techniques you need, not just by how many numbers are given.
How to play sudoku
- Fill the empty cells with numbers from 1 to 9 so that every row, every column and every 3×3 box contains all nine numbers with no repeats.
- Tap a cell, then a number on the keypad. On a computer you can also use the 1-9 keys, the arrow keys to move and Delete to erase.
- Turn on notes (the pencil, or the N key) to jot down the numbers that could go in a cell. When you place a number, the notes in its row, column and box clear themselves.
- You can undo any move. Matching numbers and conflicts are highlighted so you can read the board at a glance.
Five difficulty levels
- Very easy and Easy: to get started or to unwind; just find where only one number fits.
- Medium: you’ll need your notes and locked candidates.
- Hard and Expert: pairs, triples, X-Wing, XY-Wing and Swordfish. None of them make you guess.
Daily sudoku and statistics
There’s a new daily sudoku every day, the same for everyone. Solve it each day to grow your streak. Your statistics show games won, best time and average time for every difficulty.
Hints that teach
If you get stuck, the hint points to the next cell you can work out and explains which technique to use (last empty cell, only spot in the box, naked pair, X-Wing…). That way you learn to solve harder and harder sudokus. You can play with unlimited mistakes or with a limit of 3.
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