If you need to figure out the differences between two files on a PC then you’ve always been able to use the COMP command. And we do mean “always”: it’s been around for 30 years, since the days of DOS 1.0.

COMP isn’t exactly the most intuitive of tools, though, so if you just want to compare a couple of HTML files, say, then we’d recommend something a little more up-to-date, in the shape of the free ExamDiff.

Launch the program and you must first point it at the files you’d like to compare. Only text files are supported (the commercial Pro versions can compare binary files, directories and add many other features: see the author’s website for details).

Click OK, and both documents are displayed, side-by-side, with added, deleted or changed files highlighted.

Differences between the two files are highlighted in colour

And you can then scroll manually through your files, jump directly from one difference to the next, or even display only the differences (perhaps the best approach with very lengthy files).

Sometimes you might spot a problem, and realise that one of the files needs to be tweaked. Either of these can be edited with a click, at which point ExamDiff will recognise they’re changed, and prompt you to re-compare, so that you can see the results immediately.

You also get a useful set of configuration options, which cover everything from your preferred colours for highlighting particular changes, to how the comparison process works itself (you might choose to ignore case, ignore trailing white space, and more).

There’s even a command line interface which makes it easy to automate particular comparison operations.

And all of this comes from a program which is portable, ultra-lightweight (a 575KB executable), and runs just about anywhere (the authors say it works on anything from Windows 95 upwards).

Okay, it’s true, there’s still a place for the humble COMP command, as that also works with binary files. But if you’re looking to compare text-based documents, then ExamDiff delivers plenty of power while remaining lightweight and extremely easy to use.