# How to compare the differences between two PDF files?

Do you know a good Windows software to compare PDF files side-by-side and show the modifications between the two?

It would be great if you can post both free and not-free products.

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Try WinMerge with the xdocdiff plugin. Both are completely free. No strings attached.

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On Linux and Windows you can use diffpdf (which differs from diff-pdf mentioned in this thread).

On Ubuntu install using:

sudo apt-get install diffpdf

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Proper name is DiffPDF (as seen in the screenshot) and it's based on Qt 4 and Poppler library, thus it is portable. See DiffPDF homepage: qtrac.eu/diffpdf.html. Information about Windows build is here: soft.rubypdf.com/software/diffpdf. And your installation instruction works on Debian too. – przemoc May 22 '11 at 17:59
The DiffPDF home page now has links for Linux, Windows installer, and Mac DMG installs as well (qtrac.eu/diffpdf.html). – studgeek Oct 25 '12 at 19:37

I recently found this and I love it.

https://github.com/vslavik/diff-pdf

Cross platform, free, and works well.

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Wow, thanks @slestak - what a great tool! I've put the steps for the build process on Ubuntu Natty 11.04 in this script: get-diff-pdf.sh ... Cheers! – sdaau May 8 '11 at 6:29
Just one more note about diff-pdf: DiffPDF is great for quick visual side-by-side comparison of changed text, but it is practically impossible to debug stuff like, say, small changes in line spacing - diff-pdf on the other hand, basically puts the page contents from both compared files on the same page (but with different color) - so line spacing problems can be easily identified... Cheers! – sdaau Oct 6 '11 at 10:20

We also needed to compare PDFs at our company and were not satisfied with any of the solutions we found, so we made our own and just released version 2.0 today (9/5): i-net PDFC. It's not free, but we do offer a 30-day trial.

It's written in Java, so it's cross-platform.

What makes it special is that it compares the content as opposed to only the text (or just converting the pdf to an image and comparing the image). It also has a nice visual comparison tool.

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You can also use Adobe Acrobat X. Its has built in PDF comparison functionality under "View -> Compare Documents.

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Great tool and easy to use : Compare-It v4 (from http://www.grigsoft.com/)

Compares many different kind of files. It has some built-in converters, including one for PDF files.

I've used it quite a few times with satisfying results.

Really should try this. Trial version allows comparison for unlimited time.

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Here is a screenshot of diff-pdf in action - note that the text is not different in the PDF, but only fonts (and correspondingly, layout settings):

The call to obtain that image was:

diff-pdf --view testA.pdf testB.pdf


... where testA.pdf/testB.pdf are obtained by compiling this simple Latex file with pdflatex (accordingly for each pdf, see comment):

\documentclass[12pt]{article}

% without mathpazo: testA.pdf
\usepackage{mathpazo} % with mathpazo: testB.pdf
\usepackage{lipsum}

\title{A brand new test}
\author{Testulio}

\begin{document}

\maketitle

\lipsum[1-3]

\end{document}

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Free, Not the best but...

I open both documents up and have them split screen against each other.

Not the most practical solution, but it works!

I have not seen a good DIFF package for PDF files and whilst manual and annoying, my way works!

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Commercial: You can use the original Adobe Acrobat Professional, for a whopping \$449 :
Compare a revised PDF to an earlier version.

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@Hugh Allen: A hell of a lot of disk space and a few tens of thousands of entries in the registry. A real bloatware. – harrymc Nov 7 '09 at 10:53
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If you are comparing text inside a pdf, then Beyond Compare does this.

Not free, but there is a thirty day trial.

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Don't know it, but there is also comparePDF (not free, but a 30 day trial possible): http://www.compare-pdf.com/download.htm

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PDiff for Mac (on the AppStore). Side-by-side display of two PDFs with marked diffs, second pane with side-by-side display of the extracted texts. Differences in layout, even due to page breaks and column breaks handled smoothly. Free demo at http://www.csci.de/en/pdiff

According to the developers there will also be a windows port, however aiming at business customers (”professional" edition).

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Another less than ideal solution:

1. Convert both PDFs to Microsoft Word documents using one of the websites that do this for free.
2. Use the document comparison functionality in Word.

Depending on how complex the formatting in the PDFs is and the kind of changes you're looking for, this might be OK.

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Diff Doc - not free.

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For a very primitive form of synchronized scrolling between two pdf files, you can use the following autohotkey script I wrote. It assumes you have two SumatraPDF windows open. Press right to go to the next page in both windows, press left for the previous page.

#IfWinActive ,SumatraPDF
Right::
orig := WinExist("A")
WinGet, outvar, List, SumatraPDF
win1 := outvar1
win2 := outvar2
WinActivate, ahk_id %win1%
sendinput {Right}
WinActivate, ahk_id %win2%
sendinput {Right}
WinActivate, ahk_id %orig%
return

Left::
orig := WinExist("A")
WinGet, outvar, List, SumatraPDF
win1 := outvar1
win2 := outvar2
WinActivate, ahk_id %win1%
sendinput {Left}
WinActivate, ahk_id %win2%
sendinput {Left}
WinActivate, ahk_id %orig%
return

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I used this (non ideal, but for me sufficient) solution:

• Convert PDF to plain text (in my case with Adobe Reader, free app)
• Use opendiff (included with XCode, free) and see changes
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## protected by Community♦Oct 23 '11 at 23:41

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