Sudoku Solver

solver.p1

Prefer to play instead of solve? Try our daily puzzles — the same hint engine is built in.

How the solver works

The solver first looks for naked singles — empty cells where only one digit is legal — drawing on the same techniques covered in our guides on Naked Pairs and advanced patterns like Swordfish. When no simple deduction is available it falls back to constrained backtracking. Conflicting digits are flagged in red, and you'll be warned if a puzzle has more than one solution.