The Windoku Solver

Quite a few people have asked me to add this so I'm very pleased to get this finished at last. May be knock on bugs with the other solvers, do let me know.

Windoku is the same puzzle as normal Sudoku but with an extra constraint. In a similar way to the rows, columns an boxes, the Windows must also be uniquely 1 to 9. The paper version shows just four windows, but as is explained here there are actually nine. All Sudoku strategies continue to apply - except the ones that rely on the deadly pattern used by Uniqueness strategies.

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All feedback, comments, arguments, bug reports and strategy ideas are welcome. There is a new FEEDBACK form with a column displaying comments and questions. Many thanks to all the people who have done so and helped improve this solver.

New: Version 2.34 (Apr 9th 2025)
Added 'Hints Mode' next to Take Step. Choose between only revealing the next strategy, just the pattern or just the eliminations.

New in version 2.28.1 (14th Nov 2024)
New Packed String Definition and transport scheme

New in version 2.15, 2.16 (May 2024)
New and much faster Solution Count.
New Solution Count and Email popups.
Packed strings for transporting candidates allowed on url and import


New in version 2.14 (May 4th 2024)
Improved sanity check. Added candidate chaining and colouring.

New in version 2.10 (October 8th 2023)
Added chain cycling. If more than one chain is found the solver will provide buttons to cycle through them. Longstanding feature now implemented. More information on What's New

Version 2.05 (March 26th 2016)
Expanded Windoku to take advantage of all nine 'windows'
See Windoku Strategy documentation

Version 2.03 (November 11th 2015)
Added Windoku

Full version history here

Solver help

Use the "Import a Sudoku" button or type in a Sudoku puzzle in the small board.
You can also pick examples from the list above. Click on Take Step to step through the solution. Unknown squares are filled with 'candidates' - possible solutions.
Any cells that are reduced to one possible candidate are solved.

You can use the [<<] button to step back one go. Toggling between Take Step and [<<] helps you see the changes.

Pressing "Enter" on the keyboard after clicking on Take Step is a quick way to activate "Take Step". Details of any solutions will be written out in the text box below the big board. Strategies are ordered by complexity. Any strategy that is successful returns the step-through to the start.

Click on the board to highlight sets of numbers. You can edit the Sudoku at any time - entering solutions in the small board or editing candidates. (Toggle between highlighting and editing using the radio buttons at the top.)