ViGEm. You will need both the bus driver from the 1.8.1.0 release (1.10.0.0 is buggy) and the HidGuardian Driver + HidCerberus.Srv. Currently requires devcon.exe from the Windows SDK to install.
Open Source Agenda is not affiliated with "Switch Pro X" Project. README Source: ToadKing/switch-pro-x