How do I compare my thesis research work to commercial products that I can't obtain? My MSc thesis work in Computer Science involves developing a software solution for a particular problem for which already exist several solutions, in particular commercial software. I know I can't ignore them in my work and have to cite them, but I have no access to them, so I can't perform any comparisons to prove that my work will actually contribute to research in this field, rather than simply being another software program trying to deal with the problem. 

What's the best approach in this case?
It's my experience that software companies attempt to secure intellectual property rights for their codes in the form of patents. This is especially true in the United States. You could attempt to find information about the subject matter that you are interested in using the publicly available US Patent and Trademark Office portal, PAIR. 

A search on a company name - as applicant, or keywords in the title or abstract might get you somewhere. If you are successful, you will not - necessarily - find code. What you might get is an outline of how the patent's subject matter fits into the existing state-of-the-art. In this way, you can map out what these commercial vendors' software does and if your work will extend the subject.