Imagine the scenario, you are testing a site running an open source package but not sure what version and need to find out. The site does not include any helpful comments in the HTML and there is no README file. The package isn't a popular one so none of the regular fingerprinting apps recognise it, what can you do? Call in Sitediff, it takes a local directory of files and then requests each of them from the target site and reports back on what it finds.