It's not open-source like RANCID, but several folks are happy with Solarwinds' Network Configuration Manager (NCM).
Of course Cisco Prime LMS can back up Cisco device configurations (among many other functions). It can run on Windows, Solaris or RHEL. It's really not designed for non-Cisco gear though.
I'd estimate if you go beyond one of those 3, you'll be in an increasingly small segment of the population - single digit percentage-wise. Depending on your number and type of devices, it might be easier just to build some scripts on the mandated Windows platform and run them at AT jobs. I'd think it easier to push back on the Windows-only requirement and get an exemption to deploy RANCID on Linux.
