Does anyone know who maintains the program "rigctl.exe" ?

This program is what allows the WSPR program to do CAT control - it's part of the distribution package, and you can see it working in the command window when WSPR is running.

Unfortunately, it's out of date and doesn't support the FTDX-1200. There are probably other modern rigs not supported by rigctl.exe as well.

I don't have the tools to maintain it, but I'm hoping the original author still does.