My interest in computer checkers is waning - partly because the game is solved, partly because other interests are taking more of my time these days. I still sometimes get mail asking for new features in CheckerBoard, but I haven't done much lately. Since I don't think this will change anytime soon, I have made the source code of CheckerBoard (in version 1.651) public. This code can be used in any way you might see fit; I'm not going to bother with some kind of public license.
I am very much aware that the code is neither particularly good nor clean; CheckerBoard was - like perhaps most software - not really designed well, i.e. it started out as a simple program and then I kept on adding more and more things to it, and so the whole program structure isn't nice. Some of the source code is really old, written at a time when my programming skills were even less developed than they are now. And of course, I'm not a trained programmer who learned how to properly develop software. All of this will make the CheckerBoard source code rather hard to understand, but if you have a lot of patience and a decent working knowledge of standard C, then you can probably get to grips with it.