What techniques do the hints explain?

A naked single is a square with only one legal digit. A hidden single is the only square in a unit that can take one of its missing digits. The hint names the affected square and its rule. If neither technique applies and the grid has one completion, the solver labels its next move as a search deduction, proving the digit by exhaustive backtracking.

Can the steps finish a hard Sudoku?

Yes, for a valid puzzle with exactly one solution under the selected rules. The solver uses a search deduction when singles are exhausted. That proof does not claim to be an X-wing, swordfish or other named human technique. On an ambiguous grid it stops when it has no single rather than guessing between answers.

Will I see the entire solution when I ask for a hint?

Next square fills exactly one empty square and highlights it. You can keep asking for individual moves, switch to Check mine to validate your entries, or choose Solve all to reveal a completed grid.

Can I keep a separate puzzle on this page?

Yes. This page saves an edited draft separately from the main Sudoku Solver and the X Sudoku page. Loading it does not replace the main page's remembered puzzle.

Step by Step Sudoku Solver

Get the next proved digit without revealing the full answer. This page opens in Step mode: enter your puzzle, or load the newspaper example, then press Next square for a highlighted digit and its explanation.

Selected: R1C1

Empty grid0 givens

Press Next square for one proved digit and its explanation: naked single, hidden single or search deduction.

Entry

Givens

Solutions

not solved yet

Tap a square, then a number below the grid, or use the keyboard. Arrow keys move, digits enter, backspace erases and Enter runs the selected action. Your entries are white; solver entries are coloured. Editing or changing rules clears the solver entries. Contradicting squares turn red. Fill one proved square at a time using singles or a clearly labelled search deduction.

Three grids and what comes back

A newspaper puzzle30 givens
solved, one solution
A grid with 16 givensunder the 17 a single answer needs
solved, more than one solution
Two 5s in one columngivens that contradict each other
no solution: R1C1 and R7C1 both hold 5

Counted, not guessed. One answer means every digit is forced by the givens and selected rules. More than one means the displayed completion is one possible answer. Step labels any exhaustive search deduction separately from a naked or hidden single.

Accuracy. Exact: the answer satisfies every row, column and box, or the tool says the puzzle has none. It counts solutions as it searches, so it can tell you when a grid has more than one, and it cannot know which of those the puzzle author intended. Nothing is uploaded: the grid, the search and the counting all run in this tab, so it works with no connection once the page has loaded.

Common questions

What techniques do the hints explain?: A naked single is a square with only one legal digit. A hidden single is the only square in a unit that can take one of its missing digits. The hint names the affected square and its rule. If neither technique applies and the grid has one completion, the solver labels its next move as a search deduction, proving the digit by exhaustive backtracking.
Can the steps finish a hard Sudoku?: Yes, for a valid puzzle with exactly one solution under the selected rules. The solver uses a search deduction when singles are exhausted. That proof does not claim to be an X-wing, swordfish or other named human technique. On an ambiguous grid it stops when it has no single rather than guessing between answers.
Will I see the entire solution when I ask for a hint?: Next square fills exactly one empty square and highlights it. You can keep asking for individual moves, switch to Check mine to validate your entries, or choose Solve all to reveal a completed grid.
Can I keep a separate puzzle on this page?: Yes. This page saves an edited draft separately from the main Sudoku Solver and the X Sudoku page. Loading it does not replace the main page's remembered puzzle.

Exact: the answer satisfies every row, column and box, or the tool says the puzzle has none. It counts solutions as it searches, so it can tell you when a grid has more than one, and it cannot know which of those the puzzle author intended.