Fills the data of the sudoku you want to solve in the rectangle at the bottom (use '0' or '_' empty cells) and press import. Press any of the numbered buttons to run one round of Sudoku Solver.
One run goes through all cells and considers first the row, then the column and then the square where the cell lies to fill the cell. The number gives the size of the set considered when trying to find the value of the cell.
You can solve manually for exactly one cell: gives the row number (1 - 9), the column number (1 - 9) and when setting the set size (1 - 8) the Sudoku Solver will try to fill the cell.
You can export the state of the sudoku with the export button.