If you regularly work with PDF files then you might occasionally need to compare two documents, just to see how (or if) they differ. You could try to do that manually, but it’ll be a tedious process, and probably not very accurate. Downloading a copy of DiffPDF is a much better idea.

The program is open source and portable, so it’s straightforward to get started. Just unzip the download, launch DiffPDF.exe and you’re ready to go.

And the core interface isn’t exactly tricky, either. Click “File #1” and point the program at your first document; click “File #2” for the second; then click Actions > Compare, and within a moment or two you’ll see both documents with any differences highlighted.

If you need to know exactly how your documents vary then clicking the Next button will take you to each page where there’s a difference, so you can manually review it. If you just want to find out whether the documents vary at all, though, click the Log tab for a brief report. Or you can alternatively use the “Save As” option to save a PDF with only the pages which vary, again with the differences highlighted.

The program highlights every difference between your documents

These default settings generally work well, but there are more options available if you need them. Normally the program compares documents by word, for instance, but you can change this and compare by character, or even appearance, which will capture reformatted paragraphs, edited images and other issues.

If you know that the two files vary in some places, and only want to compare a particular page range, then you can do that, too. Just specify the pages to check – 1-3, 5-13, say – in the box to the right of each file name.

This could lead to another issue, of course – what about the page numbers? Click the Margins tab and you can define page margins which DiffPDF then ignores.

Command line support helps you automate the comparison process, very handy if you’ve a lot of files to check.

And there are several other useful options, including various settings which provide a great deal of control over how any file differences are highlighted.

Put it all together and DiffPDF is an excellent tool: fast, configurable, and generally very easy to use. Try it!