Fair warning to others, this project has no license, is Windows only and also requires an external closed-source/proprietary binary that is included in the repo.
Thanks ranger, I had completely forgotten about ControlMyMonitor.exe. That's how the program originally switched inputs, but was since replaced by win32 calls in MonitorController.cs.
I've removed that external dependency and published a new release.
Yes Windows only; I'll add mac & linux when I get a bit more time.
https://github.com/fiddyschmitt/SimpleKVM
The GUI makes things (hopefully) a little easier to set up.
It was inspired by Haimgel's project.
It's nice to be able to run the monitor at native resolution and refresh rate, without paying hundreds for a KVM.