Sudoku Susser : Freeware Sudoku Solver & Assistant (Projects)

Current Version : 2.5.8

Note: I am no longer actively maintaining this app because it would require paying $$$ to update a development environment, and I can't justify that. I hope to be able to revisit this decision at some point in the future – Robert

Links to download the latest version are at the bottom of the page.

Note: as of March 2017, the site is blocking the Susser from automatically downloading puzzles. I have emailed to ask why, but have not received a reply. However, you can still use a browser to find puzzles on the site, then select-all/copy and paste them into the Susser.

The Sudoku Susser is a program that helps you play Sudoku. You can use it for free but you are encouraged to tip the author the amount you think it is worth. The decision to tip, and the amount, are entirely up to you. The program is distributed with no crippleware or nag features whatsoever.

If you've been living under a rock and don't know what a Sudoku puzzle is, the London Daily Mail has a good introduction to the puzzles and basic solving techniques. I have also created an introduction to Sudoku puzzles and the basic solving techniques, written for children, which you may find useful.


The Sudoku Susser makes it easy to make your selections as you solve the puzzle; just click on one of them and select the new number from the popup menu that appears, or mouse over it and press the number on the keyboard. But it does far more than that!

It can display the remaining possibilities for each square in several ways, making it easier for you to see the patterns that are the key to solving tough puzzles. You can add and remove possibilities as you make inferences about the puzzle.

It can hilight 14 different simple and advanced Sudoku patterns. Everything from simple forces and pins up to mega-expert techniques like forcing loops and chains.

It can give you hints on how to proceed, or solve the puzzle by human-style logic, with detailed explanations of the steps. No known puzzle can stump the Susser's heuristic deduction engine.

Other features:

  • You can drag Sudoku graphics from just about any webpage and they'll be scanned and loaded into the application.
  • Instant download of new puzzles from the Sudoku archive (and other popular puzzle sources)
  • Extensive help, hint and hilighting features show you the logical structures in the puzzles.
  • You can manage, rename, reorder, and print out your Sudokus.
  • You can drag them out of the app as graphics or in a variety of text formats.
  • Undo and redo are fully supported.
  • Many sample puzzles to get you started.
  • Comprehensive manual gives detailed explanations of all the advanced solving methods the program can use.

Release Notes

Version 2.5.8 of 2008-03-29

* Bug fix in 2.5.6 caused paste of text puzzles to sometimes fail if a log panel had the focus; this has been fixed.

* Relaxed a restriction in the Consequence Trees hilighters that caused it to sometimes miss contradictions that had a common “trunk” path. While it's arguable that this restriction is reasonable (and I'll argue it, damn it!), it's pedantic, unhelpful to the user, and sometimes caused the hilighter to report a verity that, while it had correct implications (and wouldn't steer you wrong), wasn't a “real” verity. Kudos to Setemkia (Fawn) Falling Tree for noticing this.


You can find archives of the Susser for Mac, Windows and Linux, as well as documentation PDFs, here.

The Macintosh version of Sudoku Susser runs on Mac OS X 10.2.8 or better.

The Windows version of Sudoku Susser runs on Windows 98, NT (4.0 or higher), ME, 2000, 2003 Server, and XP (and probably later)

The Linux build of the Susser is totally untested, no idea if it works! System requirements are: Any x86-based Linux distribution with GTK+ 2.0 (or higher), glibc-2.3 (or higher) and CUPS (Common UNIX Printing System), which includes: Red Hat Enterprise 3, SuSE Linux 8.1 (and higher), Mandrake Linux 9.1 (and higher, including Mandriva) You may also need recent versions of the following packages: glib-2, pango, atk, openssl, zlib, and expat.

©;2005-2008 Robert Woodhead. Sudoku Susser™ is a trademark of Robert Woodhead.

The Sudoku Susser is tipware. Use it for free, and if you like it, then send me what you think it's worth. There's a PayPal button in the application that makes it easy, and other information in the manual if you prefer not to use PayPal.

Written in RealBasic. Use at your own risk (not because it's written in RealBasic, because it's written by me!)

Comments & bug reports to