Sudoku: Scan, Solve, Learn

Sudoku that teaches you to solve, not just a grid to fill in.

SCAN A PUZZLE FROM PAPER
Are you stuck in a Sudoku ? Point your camera at a sudoku scan it and see how to unlock the next move. Recognition runs entirely on your device using a neural network trained specifically for this app — nothing is uploaded, and it works with no internet connection at all.

Because no scanner is perfect, every scan stops at a review screen before it reaches the board. You see the photo with the detected grid drawn over it, all 81 cell crops next to what was read from each one, and the confidence behind every digit. Anything misread can be corrected with a tap. Cells that repeat a digit in their row, column, or box are flagged in red, so a bad scan can never become an unplayable board.

UNDERSTAND EVERY MOVE
Ask for a solution and you don't just get answers — you get reasoning. Each digit is placed one step at a time, and the technique behind it is named and explained in plain English as it happens:

• Naked Single — a cell has only one candidate left
• Hidden Single — a digit fits only one cell in its row, column, or box
• Pointing Pair and Box/Line Reduction — locked candidates
• Naked Pair, Hidden Pair, Naked Triple
• X-Wing and XY-Wing
• Nishio — trial and contradiction, used only as a last resort

Pause the solver at any point to study the board yourself, step backwards and forwards through the reasoning, then resume when you're ready. The running commentary makes it a tutor rather than a cheat button.

PUZZLES THAT ARE ACTUALLY FAIR
Every generated puzzle is checked to have exactly one solution — never two, never ambiguous. Each is also graded by the hardest technique it genuinely requires, and any puzzle that can only be finished by trial and error is thrown away. If you reach a wall, there is always a logical way through.

Five levels, from a single match to a full volcano: Easy, Casual, Medium, Hard, Expert. The harder tiers are harder to think about, not merely emptier.

BUILT FOR COMFORTABLE PLAY
• Pencil marks, with automatic clean-up as you place digits
• Auto-notes to fill in candidates for a cell
• Safe mode highlights a conflict the moment you create one
• Hint button points out a cell that has only one possibility left
• Full undo and redo history
• Four colour themes: Midnight Focus, Warm Paper, Forest Minimal, Slate Contrast
• Portrait and landscape
• Progress stats for solved puzzles and help used

PRIVATE BY DESIGN
No account. No ads. No tracking. No analytics. No network access of any kind — the app has no code to reach the internet. Your photos are read on your device and never leave it.