sudoku-solutions.com - Sudoku Tutor and Solver

This solver offers a number of features
to help you improve your solving skills and practice solving
strategies. First enter the numbers of the sudoku directly in the
grid or enter them via the "Load" and "Seed" buttons. You can then
completely solve the puzzle or use the appropriate buttons to check
the validity of the puzzle, get tips for step by step solving and
much more. See the button descriptions below for more information.

This is what the buttons do: