Ever get a Visio document and wonder what’s inside it? There are a few paid programs on the Mac that view Visio documents, but they are a bit spendy when you just want to see the file. Instead, grab LibreOffice.
LibreOffice is a full office suite and it has the ability to read Visio files. It may not be prefect, but it’s a lot better than dropping $100 on OmniGraffle.