Does Viewer run on Windows? Mac? Linux?

Yes.

Steelray Project Viewer runs on Windows (Vista, Windows 7 32-bit and 64-bit, Windows 8 32-bit and 64-bit, Windows 10 32-bit and 64-bit), most Linux distributions, and Mac OS X (10.6.4 or later).

Let us know if you're interested in another operating system (and have deep pockets).