It is true that finding something is difficult. I went on sourceforge.net and only found a chorderator project developed in c# that was no longer active. The screenshots are attractive, however, I was unable to get the program to operate on my computer. It's likely that you'll need to install Visual Studio or something similar. I'm hoping you have better luck. In any event, there appear to be a plethora of chord generators on the web and on Sourceforge, not all of which are in c#, but which you could definitely hack into c#.
Link for chorderator : https://sourceforge.net/projects/chorderator/