Reliable way to (programmatically) compare PDFs? [duplicate]

Answer 1

I am a developer of Docotic.Pdf Library. We use PDF comparison in unit tests for checking that test produces PDF as expected. PDF is a collection of special objects and we compare all PDF objects ignoring some properties like trailer IDs and creator info. This implementation works fine.

You can try the method PdfDocument.DocumentsAreEqual. This method just tell you are documents equal, without specific differences. You may contact us if you need more functionality.

Answer 2

I went the approach to getting the raw data out of the PDF, then making use of Word or TortiseSVN, or WinMerge, etc...to take care of the comparison piece. In my instance I did the comparison in a RichTextBox in C#...coloring the differences, etc...since we wanted it all within our app.

Here is what I did... PDF comparison as I was trying to compare mixed documents, Word and PDF.

However I would recommend PDFBox for the parsing, a bit more elegant...although iTextSharp worked out ok...

Answer 3

There is quite a few software products that claim to diff pdfs. I've never had need to use one but if this is going to be a recurring process I think it'd be wise for your company to invest in one of them. Just Google "pdf diff" for a bunch of potential applications.

Additionally, your situation is very similar to this question: Tool to compare large numbers of PDF files? I think its discussion may help.

Answer 4

I wrote a blog suggesting some approaches to comparing PDF files at https://blog.idrsolutions.com/2010/09/comparing-2-pdf-files/