How to use it

A solver for learning, not guessing

A good Sudoku solver should do more than print the answer. ZUDOKU checks whether the puzzle is valid, counts solutions up to the uniqueness threshold, shows candidate digits, and gives a human-readable next step when the board has a logical move.

Use the checker when you create or import a puzzle. A proper classic Sudoku should have exactly one solution. If the grid has no solution, the tool points to conflicts. If it has more than one solution, the puzzle is not suitable for serious play.

Use the hint card when you are stuck. ZUDOKU now follows a human solve path with naked singles, hidden singles, locked candidates, naked pairs, and hidden pairs, then rates how far logic can carry the board before advanced patterns are needed.