The simplest is to use tkinter, it should run directly after download for most scientific-related Python installs on Windows. The user interface for all GUI versions is identical, the different versions exist because different developers use different Python libraries for making GUI applications and I tried to cover all of them. These GUI versions do not have User Defined Functions or Function Finders, as those make the GUI interface more complicated. The web site code itself does not run on Windows as it uses a Unix-like "fork" operating system call, but now that Linux can be run on Windows it might work - I have not tried this. I have verified that the web site code does run on a Raspberry Pi, though somewhat slowly.
James