# How to compare the differences between two PDF files on Windows?

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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–  Epaga Sep 10 '12 at 9:28

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

A couple of the comments below suggest they don't see any difference. That means the plug-in isn't installed correctly. Here's how:

1. Put the files where the xdocdiff plugin's readme file says to put them (there are two places; I won't list them here as filenames can change, etc. — read the readme)

2. In WinMerge, go to Plugins > List and tick the "Enable Plugins" checkbox (this step is missing from the xdocdiff readme)

3. In WinMerge, choose Plugins > Automatic Unpacking (this was disabled prior to step 2)

Then when comparing, you'll see what look like text files in the comparison windows.

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Plugins > List and tick the "Enable Plugins" checkbox was what was missing for me! –  Seph May 5 '14 at 11:28

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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cross your eyes so that the two copies overlap, and any differences will appear to flicker. :D –  endolith Mar 4 '14 at 16:12

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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Commercial: You can use the original Adobe Acrobat Professional, for a whopping $449 : Compare a revised PDF to an earlier version. If you decide on Acrobat, the comments on this page are pertinent to its use. - @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 Diff Doc - not free. - 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. - This was the best and easiest of all for me. Thanks! – Ankur Jain Apr 18 '12 at 7:41 If you are comparing text inside a pdf, then Beyond Compare does this. Not free, but there is a thirty day trial. - You can also use Adobe Acrobat X. Its has built in PDF comparison functionality under "View -> Compare Documents. - Acrobat or Acrobat Reader? the Reader software doesn't have this – Jason S Nov 28 '12 at 17:06 AcrobatX Pro is the only version which has this feature. The "just plain AcrobatX" does not. – Carl Witthoft Feb 20 '13 at 21:16 Don't know it, but there is also comparePDF (not free, but a 30 day trial possible): http://www.compare-pdf.com/download.htm - I recently found this and I love it. https://github.com/vslavik/diff-pdf Cross platform, free, and works well. 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}  - 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 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  - 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 As of this writing DiffPdf on Windows has a minor problem when the 2 PDFs differ in length - both appear to end when the shorter one does. For example if I have a one-page PDF doc, and someone added in places all over it to bring it to 2 pages, the diff compares the first page of each, and does not show the second page with the parts that have been added. – Chris Moschini Mar 9 '13 at 21:14 DiffPDF is the most advanced tool presented here, in my opinion. Not only does it offer a nice graphical comparison, but it tracks changes more cleverly than others, e.g. the xdocdiff for WinMerge. However, it has one serious problem: It limits the comparison to pages. That means, if you have some text on page 2 of document A, but this text moves to page 3 in document B, then the tool thinks its gone in A and added in B. – Marco W. Mar 29 '14 at 1:31 The older free versions can be found here – Shafik Yaghmour Jun 4 '14 at 12:29 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). - 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  - 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: 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. - Nice bit of software. – Umber Ferrule Sep 18 '12 at 9:53 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 - I wanted to do this (diff PDFs) recently with these requirements: • ignore whitespace, line breaks, page breaks, etc. • easily see when just a couple words that changed, not just entire lines/paragraphs. • color diff output I installed pdftotext, wdiff, and colordiff, available in various package managers. (With macports: sudo port install poppler wdiff colordiff) Then: wdiff <(pdftotext old.pdf -) <(pdftotext new.pdf -) | colordiff Now I can see which words, nicely colored, have changed. Variation: Using dwdiff can produce slightly better results. I also wanted HTML output so this tiny script makes a basic web page with a bit of CSS. bash pc-script.bash old.pdf new.pdf > q.htlm Then open q.html with your web browser. pc-script.bash file: #!/bin/bash OLD="$1"
NEW="$2" cat <<EOF <html><head><meta charset="UTF-8"/><title>Changes from$OLD to $NEW</title></head><style> .plus { color: green; background: #E7E7E7; } .minus { color: red; background: #D7D7D7; text-decoration: line-through; } </style><body><h1>Changes from [ <span class="minus">$OLD</span> ] to [ <span class="plus">$NEW</span> ]</h1><pre> EOF dwdiff -i -A best -P \ --start-delete='<span class="minus">' --stop-delete='</span>' \ --start-insert='<span class="plus" >' --stop-insert='</span>' \ <( pdftotext -enc UTF-8 -layout "$OLD" - )   \
<( pdftotext -enc UTF-8 -layout "\$NEW" - )   \

cat <<EOF
</pre></body></html>
EOF


An example of output can be seen here

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