Sudoku online
Four difficulty levels, full keyboard control and nothing in your way. Pick a level and play.
Pick a difficulty and play
Four levels of the same game. The further right, the fewer digits you start with.
- Easy Level 1 of 4. Just fill in the digits that have only one option left. A good place to start. Play
- Medium Level 2 of 4. You now have to rule digits out of a row, a column and a box on purpose. Play
- Hard Level 3 of 4. Few digits to start with. Needs pairs and triples, not just looking. Play
- Expert Level 4 of 4. Minimum clues. For people who count their time in seconds. Play
The daily challenge and the global leaderboard are coming next. Free play works now — your times are kept in this browser.
Four levels, in practice four different games
A difficulty level here is two things at once: how many digits you see at the start and which techniques the board demands. That distinction matters more than it looks — a board with 24 clues that only ever needs obvious moves is slower for a human than a board with 34 clues that needs one clever step. So we calibrate both, not just the number of blanks.
- Easy sudoku — 32 clues. Everything falls out of spotting single candidates. Right for a first puzzle and for warming up.
- Medium sudoku — 28 clues. The first level where pencil marks genuinely pay off.
- Hard sudoku — 25 clues. Pairs, triples and locked candidates are required.
- Expert sudoku — 21 clues. Minimum hints, for people who solve sudoku regularly.
Every board is generated from scratch and checked for one thing: that it has exactly one solution. If you ever have to guess, it means you entered a wrong digit earlier — not that the puzzle is unfair.
Sudoku rules in three sentences
Fill the 9×9 grid so that every row, every column and every 3×3 box contains each digit from 1 to 9 exactly once. The digits printed at the start never move — you only add the missing ones. There are no extra rules, no arithmetic and no required order.
How to play here
The controls are built to stay out of your way:
- Keyboard — arrows or WASD to move, digits 1–9 to enter,
Delto erase. No input lag after a keypress. - Pencil marks — space or
Ntoggles them. Entering a digit clears the marks it invalidates across the row, column and box. - Undo —
Zundoes,Shift+ZorYredoes. Full history, not a single step back. - Three-mistake limit — a wrong digit costs a life and stays marked in red with a strikethrough. The third mistake ends the board.
- Conflict highlighting — on for easy and medium, off by default on hard and expert. Toggle with
H. - Saved game — reloading the page loses nothing: you come back to the same board, the same time and the same mistake count.
- Dark mode — follows your system setting, nothing to click.
- Touch screens — a number pad below the board, so the system keyboard never covers half the screen.
Who this is for
- Beginners — start on easy. The mistake limit stops you from grinding on a board that is already broken.
- Anyone who wants calm — a large, high-contrast grid, clear digits, no animations and no pop-ups. Ignore the timer if you like; nothing here rushes you.
- Serious solvers — full keyboard control, a precise timer and expert boards with 21 clues.
You play with no sign-up, no email and nothing to download. Personal records are kept in your own browser.
What is coming next
This site exists to compare solving times honestly: one daily puzzle identical for the whole world, leaderboards across five time windows, a percentile like "faster than 87% of players" and a country ranking. None of that is live yet — today free play across four levels is. Records you set now will stay where they are when the daily puzzle arrives.