Sudoku 👣

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You have an unfinished puzzle.

Puzzle Complete!

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Highlights

Row, column & box

Matching numbers

Legal placements

Errors

Hints

Tutorial mode

Clear all?

All answers and notes will be cleared.

Position the grid corners

Drag each numbered marker to a corner of the Sudoku grid.

Crop around the puzzle

Drag the red handles to remove everything outside the Sudoku.

How to Play

Hint & Peek

Tap 🔍 Hint to highlight a cell the solver recommends as a good next move. The button changes to 👁 Peek. Tap Peek to reveal the answer for whichever cell is currently selected — it doesn't have to be the highlighted one. The hint clears once the highlighted cell is filled.

Notes Mode

Tap ✏️ Notes to switch digit buttons from placing an answer to toggling small pencil-mark candidates. Tap again to return to answer mode. Notes are automatically removed when a related cell is filled.

Fill Candidates

With a cell selected, tap ✍️ Fill to fill that cell's notes with every currently valid digit. With nothing selected, it fills the whole board at once.

Conflict Check

In ⚙️ Settings, turn Errors on to highlight conflicting digits in red. When on, any digit you enter that already appears in the same row, column, or box is highlighted red. This checks only against digits you've entered — not the solution — so an incorrect digit that doesn't duplicate anything won't be flagged.

Remaining Count

The small number in the corner of each digit button shows how many of that digit are still to place. The button dims when all 9 are used.

Apple Pencil

Tap any cell with the Pencil to select it, then write a digit with Scribble to enter it. The green tint on the selected cell means Scribble is ready to receive handwriting. You can also tap the numpad buttons directly with the Pencil.

Solving Techniques

When a hint is shown, the pill names the technique and the grid highlights it: purple cells are the pattern that justifies the move, and lighter muted-purple cells are candidates being eliminated. Multi-step hints can be stepped through with the ‹ › buttons on the pill. Here's what each technique means:

Easy

Naked Single: A cell has only one candidate left, so it must be that digit.

Medium

Hidden Single: A digit has only one possible cell left in a row, column, or box, even though that cell still shows other candidates too.
Naked Pair: Two cells in the same row, column, or box contain only the same two candidates, so those two digits can be removed from every other cell in that unit.

Hard

Pointing Pair/Triple: A digit's candidates within a box all fall in a single row or column, so that digit can be removed from the rest of that row/column outside the box.
Box-Line Reduction: A digit's candidates within a row or column all fall in a single box, so that digit can be removed from the rest of that box.
Hidden Pair: Two digits only appear as candidates in the same two cells of a unit, so every other candidate in those two cells can be removed.

Very Hard

Naked Triple: Three cells in a unit contain only three candidates between them, so those three digits can be removed from the rest of the unit.
X-Wing: A digit's candidates in two rows fall in the same two columns (or vice versa), forming a rectangle that lets you remove that digit from the rest of those columns or rows.
Swordfish: Like an X-Wing but spanning three rows/columns instead of two — the wider pattern still lets you remove the digit elsewhere in those lines.
XY-Wing: Three cells with exactly two candidates each link together so a shared digit can be removed from any cell that sees both of the outer two cells.
Unique Rectangle: Four cells forming a rectangle across two boxes would allow two different solutions if left alone — since a Sudoku has only one, the extra candidate causing that can be removed.