Welcome to my online javascript-based Sudoku solver. As each number is entered into the puzzle other (logically) solvable values will be populated automatically. To remove or change an entered number simply un-check the checkbox beneath it.

If you need some help simply hover over any empty box and you will see the available numbers left for that box. Voila!

NEW! When boxes have become "over-constrained" (i.e. when there are no possible solutions remaining) then they will turn red. This indicates that the puzzle, in it's current state, is unsolvable for those boxes. You should remove a locked value (most likely the number you just entered).

Send questions or unsolvable puzzles to: sudokuSolver AT shannonandmike.net

When you are dealing with "very hard" puzzles it is likely that the "available numbers" list will include invalid possibilities. Try different solutions and pay attention to "over-constrained" boxes.

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This work is wholly created by Michael Barron but may be licensed under a
Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.