What is a Sudoku helper?
A Sudoku helper is different from a Sudoku solver. A solver can finish the whole grid, while a helper focuses on the next useful step: candidates, contradictions, highlights, and hints that keep you involved in the puzzle.
This page targets everyday Sudoku helper use: enter your puzzle, press Next Hint, read the explanation, then decide whether to apply the move or return to solving on your own.
How to use this Sudoku helper
Click a cell and enter digits with the number buttons or keyboard. You can also import a standard 81-character puzzle string, where 0 or . means an empty cell.
The first press of Next Hint fills pencil marks. The next press scans for available techniques and links the hint to a short explanation further down the page.
Sudoku helper technique explanations
These are brief explanations for the techniques the helper can detect. They are intentionally compact, so the tool remains focused on solving rather than turning the page into a full strategy course.
Naked Single
BeginnerA naked single appears when an empty cell has only one possible candidate after row, column and box rules are checked. The helper can place that digit directly.
Pointing Pair
IntermediateA pointing pair or triple happens when all candidates for a digit inside one box sit on the same row or column. That digit can be removed from the rest of that line.
Box/Line Reduction
IntermediateBox/line reduction works in the opposite direction: when a digit in a row or column is locked inside one box, it can be removed from other cells in that box.
Naked Pair
IntermediateA naked pair is two cells in the same unit with the same two candidates. Those two digits must occupy the pair, so they can be removed from other cells in the unit.
Naked Triple
IntermediateA naked triple uses three cells whose combined candidates are three digits. Those digits are reserved for the triple and can be removed elsewhere in the unit.
X-Wing
AdvancedAn X-Wing forms when a digit appears in the same two columns across two rows, or the same two rows across two columns. It removes that digit from matching lines.
Swordfish
ExpertA Swordfish is a three-line version of X-Wing. If a digit is locked into the same three columns or rows, the helper removes it from other matching cells.
Jellyfish
ExpertA Jellyfish extends the fish pattern to four rows or columns. It is uncommon, but useful when easier candidate eliminations have run out.
XY-Wing
AdvancedAn XY-Wing uses three two-candidate cells. The pivot sees two wing cells, and any cell that sees both wings can lose the shared candidate.
XYZ-Wing
AdvancedAn XYZ-Wing is similar to XY-Wing, but the pivot has three candidates. Cells that see the pivot and both wings can lose the common digit.
W-Wing
AdvancedA W-Wing links two matching bivalue cells through a strong link. The shared elimination digit can be removed from cells that see both ends.
Skyscraper
AdvancedA Skyscraper uses two strong links for one digit arranged across two rows or columns. Cells that see both roof positions can lose that digit.
Simple Colouring
AdvancedSimple colouring follows strong links for one digit and marks alternating possibilities. A contradiction or shared view can reveal eliminations.
Unique Rectangle
AdvancedA unique rectangle avoids a pattern that would allow two solutions. When the rectangle conditions are met, extra candidates can be removed.
Almost Locked Set
ExpertAn almost locked set has one more candidate than cells. When two sets are linked in the right way, the helper can remove a shared restricted candidate.