Sudoku
Sudoku, solved right.
Every puzzle here is generated automatically, kept stocked and ready, and checked by a real backtracking solver before it ever reaches your screen — guaranteed to have exactly one solution. So if you get stuck, the puzzle is never the problem.
No account needed — jump straight into a puzzle.
- Difficulty tiers
- 6
- Valid solutions per puzzle
- Exactly 1
- Moves forgotten
- 0
Built to earn your trust, one grid at a time
Nothing here is hand-waved. Every claim below is something the app actually does, not just says.
No guesswork puzzles
Every board is generated, then dug down to size while an exhaustive solver keeps checking that exactly one solution remains. A puzzle that turns ambiguous never gets dealt to you.
Fair difficulty, not vibes
Easy through Extreme come from one fixed rubric — the hardest reasoning step your solution needs, the same signal a serious solver rates by, not how many clues the board happens to start with — and every puzzle also carries its own Logic required badge naming that exact step and the technique behind it. Both labels are measured before you play, never picked by hand.
One shared puzzle every day
A new challenge lands on a fixed schedule — one board for everyone, generated ahead of time so today's is always playable from any timezone or device. Difficulty cycles through all six tiers across a six-day rotation, each daily keeps the usual single-solution guarantee, and no board is ever featured twice.
Catch up any day, keep your streak
Play today's like any other puzzle here — your own session with all the tools — or come back to a missed one later; either way completion counts toward its scheduled date. Your month calendar fills in as you solve, current and longest streaks sit right there, and an archive lets you browse past dailies by difficulty.
Pick up where you left off
Every move you make is saved the moment you make it. Your dashboard always shows the boards you have in progress, ready to continue.
Every board, sorted by where you left it
Puzzles are shared property here — every board anyone has built or generated is open to everyone. The library splits them into what you're currently playing, what you've never touched and what you've already finished, so finding your next one never means scrolling past the last one.
A full record of how you solved it
Nothing about your play gets summarized away. Every move is logged in order, so you can look back over your exact path to the solution — and when a play ends, that log adds itself up for you: placements made, accuracy, mistakes, and how your total compared with an optimal line through the same board. Want to watch it back? "Watch your solve" steps through your own moves, or the puzzle's own optimal line, one at a time.
Know your numbers
A stats page tracks puzzles solved, win rate, accuracy, and best and average time — combined, and broken out across all six difficulty tiers. Beat a puzzle once, and its page keeps showing your personal best time for it from then on.
Play smarter, not harder
Select a cell to highlight its row and column; select a filled one to see every other cell holding that digit. A number pad keeps entry fast, and Notes mode pencils candidates into any cell without ever losing your place on real digits. When you'd rather start from a full picture, one tap auto-fills every cell's candidates at once — and placing a digit for real prunes it from the rest of its row, column and box for you. Change your mind? Undo and redo step back through every move and pencil mark, no penalty attached.
Bring your own puzzle
Type in any board and the same solver checks it live — solvable, unsolvable, or ambiguous — before you commit to playing it.
Hints that teach instead of answer
Stuck? Ask for exactly one step forward. Each hint names the technique it uses, shows why it works, and rings the actual cells on your board — the pattern it's reasoning from, and the cell or candidate it's pointing at — so you learn from being stuck rather than just getting unstuck.
A page behind every label
Every named reasoning move gets its own explainer, linked straight off the puzzles that rely on it — and it isn't a wall of text. You pencil the pattern in yourself on a real board, the reasoning unfolds a step at a time as you do, and then you make the move it was pointing at. A rating here is never just a word.
Play on your terms
Each play runs on settings you control — quick presets like Zen, Newspaper or Tournament set timer, highlight assist, instant feedback and mistake limits in one tap, and your defaults live where you can change them any time. Need to step away? Pause freezes the clock — and switching tabs pauses it for you, so a timed run is never quietly thrown off by an interruption.
Keyboard and screen readers
The whole board plays without a mouse
Not a grid of click targets with a few shortcuts bolted on afterwards. The board is a real ARIA grid, and every part of a play — reaching it, moving around it, placing digits, pencilling candidates, jumping straight to a cell — has a key behind it.
- One tab stop, not eighty-one
- The cells share a roving tab stop, so one Tab reaches the board and the next moves past it to the digit pad — Tab never walks you through 81 squares to get anywhere.
- You never have to click in first
- An arrow key pressed anywhere on the page, with nothing else focused, walks you onto the grid at its top-left cell. Type into a field or open a dialog and those same keys go straight back to meaning what they mean there.
- Every cell says where it is
- Each one is labelled with its row and column, what it holds, whether it's a fixed clue, and any candidates pencilled into it — so a screen reader reads a place on a board, not a loose digit in a table.
- Changes are spoken, not just shown
- A live region reports what the board alone can't: the notes pad opening, a jump waiting on its next digit, anything that changes while your focus stays put. And a placement made from the keyboard hands focus back to the cell you made it on, so you never lose your place mid-board.
Every key the board listens for
- ↑ ↓ ← →
- Move between cells — W A S D work too
- Home End
- First or last cell in the row; hold Ctrl for the whole board
- Ctrl 1–9 1–9
- Jump straight to a cell — tap Ctrl on its own, then the row digit and the column digit
- 1–9
- Place that digit in the selected cell
- Shift 1–9
- Pencil a candidate, whether or not the notes pad is showing
- 0 Backspace
- Clear the selected cell
- N
- Show or hide the notes pad
- Esc
- Deselect the cell and clear its highlights
The same list sits in the How to play dialog on every puzzle.
Three steps to your next puzzle
Just start playing
No sign-up, no email to verify — hit Play now and you're straight into a puzzle as a guest. Create an account later, only if you want that progress to follow you to another device.
Pick one or design your own
Grab a freshly generated puzzle from the library, or build your own and have it verified instantly.
Solve with real tools
Highlighting, pencil marks (by hand or auto-filled), a number pad, on-demand hints and a full move history stay with you from first cell to last.
Ready to sharpen up?
Your next puzzle is one click away — and it's guaranteed to be solvable.