Help on the Sudoku in front of you

Photograph the Sudoku you are stuck on.

Use a puzzle from a newspaper, book, website, or another app. doku.su reads the printed numbers on this device, explains the next logical step, and remembers what tripped you up for short practice.

Show me the next logical move →No account required · Recognition stays on this device

From image to explanation

Keep your puzzle. Add a coach.

This is not a solver that replaces your work. You review the recognized givens, then continue playing while progressive clues teach the next deduction.

01
Choose the image
Take a straight photograph of a printed grid or choose a screenshot already saved on your device.
02
Check the recognized grid
Uncertain squares are marked for review. You can correct any number before continuing.
03
Ask for the next logical move
The coach works from the current grid, names the technique, and reveals only as much as you request.

Before you play

Checked before coaching begins

Conflicting givens are rejected.
The puzzle must have one valid solution.
Incorrect entries are marked during play.
The coach uses deterministic Sudoku facts.

First coached hint

Your first hint protects the solve.

After you confirm the recognized grid, the coach starts with where to look. If you ask for more, it reveals the cell and then the reason before any digit. For candidate-based moves, the reason checks which digits remain legal in the relevant row, column, and 3×3 box. A candidate list narrows the search; only the complete check proves the move.

Confirm every uncertain square against the image.
Start the imported puzzle and choose “Show me where to look.”
Check the highlighted area yourself, then reveal only the next clue you need.

Recover without losing the grid

If the photo cannot be verified

Blurred or cropped grid: retake the photo straight above the full grid, or choose a clearer image.
Wrong recognized number: select that square and correct it before continuing.
Conflicting givens: compare the marked row, column, or 3×3 box with the source image.
No unique solution: recheck missing or mistaken givens; coaching begins only after the grid is valid.

Interactive lessons

Practise the check behind the hint.

Use the scanning lesson to choose an area, the candidate-notes lesson to verify legal digits, or the technique library to practise the named pattern on a different grid.

Practise scanning Practise candidate notes Open the technique library →

You control whether an image is shared.

Recognition runs locally on this device. Your image is uploaded only if you later choose “Help improve photo recognition,” preview the exact image, and explicitly consent. Imported puzzle progress remains on this device unless you choose account sync.

Photograph a Sudoku

Use the coach on the grid that stopped you.

Choose the screenshot or photograph, check the recognized numbers once, and continue from the exact puzzle you wanted to solve.