The software can be obtained using the Mac App Store application on OS X systems. The current cost is $4.99 USD. After installation of the software, you will see a VSD Viewer Pro app in the system's Applications folder. You can double-click on the app there to open it and then click on File and Open to select the Visio file you wish to open. Or, once you have the program open, you can just drag a Visio file onto the "VSD Viewer Pro Drop Zone" to open the file.
VSD Viewer Pro is a Visio file viewer program; you can't edit Visio files with the software, but you can read .vsd, .vsdx, .vsx, .vss and .vssx documents and can save as PDF or image files. The software provides the capability to zoom in and out while viewing files and rotate the image displayed.
The software uses the following libraries: libwpd; libwps; libwmf; libwpg; libgxps; freetype; gio; glib; gmodule; gobject; gthread; cairo; libintl; openTNEF; libpixman; libarchive; libgd; mimetic; liblcms2; canvas; boost; libffi; libjpeg; libtiff; libpng.
I need to view Visio files created by others who use Microsoft Windows systems and I've been very happy with the VSD Viewer Pro software, which has been able to display all of the Visio files I have needed to view on my MacBook Pro laptop running OS X Yosemite (10.10.5).