Sudoku LunaSudoku Luna

Sudoku Solver

Type in the puzzle you are stuck on and see the whole solving path: every step names the technique it uses, shows which cells prove it, and links to the lesson. No guessing anywhere — where logic alone is not enough, the solver says so.

0 of 81 cells filled

Questions about the solver

Is the solver free?
Yes. There is no sign-up, no limit on how many puzzles you enter and no cost.
Does it just give me the answer?
Only if you ask for the last step. The point is the path: each step names the technique, highlights the cells that prove it and links to the lesson, so you learn the move rather than copy the digit.
What if my puzzle has no solution?
The solver tells you. It checks for duplicate digits first, then whether a solution exists at all, then whether it is unique — a grid with several answers gets flagged instead of quietly having one picked for it.
Which techniques does it use?
Twenty, from full houses and singles through locked candidates, subsets and fish to wings, colouring and forcing chains. It always tries the simplest technique that works, so the path stays readable.
Can I share a puzzle with someone?
Yes. The puzzle is encoded in the address, so copying the link is enough — whoever opens it sees the same grid and the same solving path.

Difficulty levels