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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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Related:… –  Epaga Sep 10 '12 at 9:28
There is a FREE library to compare pdf pixel by pixel. Check this blog:… –  Vinoth S Jun 16 at 23:35

15 Answers 15

up vote 67 down vote accepted

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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Tried this but couldn't see any difference when not using the xdocdiff plugin. Is there an option to select in WinMerge's UI? –  Umber Ferrule Sep 18 '12 at 9:53
What is the purpose of viewing the binary text in a PDF? I expected to see the visual differences as done by i-net PDFC. –  JJD Jan 4 '13 at 11:03
Was there any way to make this handle column breaks? Without it one change cascades into several. –  Stuart Apr 29 '13 at 23:48
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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Hum... not quite what I was looking for, but thanks. –  Nelson Reis Sep 24 '09 at 9:50
Sorry, I know not a good answer but just saying that I have never found a good tool for PDF files. –  William Hilsum Sep 24 '09 at 9:55
That's what I'm afraid of... thanks again! –  Nelson Reis Sep 24 '09 at 10:03
cross your eyes so that the two copies overlap, and any differences will appear to flicker. :D –  endolith Mar 4 '14 at 16:12
Optimized version of this method: open both PDF files in acrobat reader full screen via CTRL+L, then use CTRL+F6 to switch between the PDF files, anything that moves is different... –  Bernard Vander Beken Jun 18 '14 at 13:12

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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In this case it would be hard, since there are lots of PDF documents and the modifications happen very frequently. But thanks for the suggestion. –  Nelson Reis Sep 24 '09 at 10:20
Also not great for LaTeX output - I haven't found one of these converters that handles ligatures etc properly. –  Chris H Sep 3 '13 at 10:19

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.

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"for a whopping $449" ... and how many MB of disk space? –  Hugh Allen Nov 7 '09 at 6:17
@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
Updated help article for Adobe Acrobat XI: –  Squig Sep 23 '13 at 14:44
And it's buggy anyway: –  Michal Sokolowski Jul 20 at 12:42

Great tool and easy to use : Compare-It v4 (from

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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This was the best and easiest of all for me. Thanks! –  Ankur Jain Apr 18 '12 at 7:41
Easiest and most simple tool I found to use. I wish I could upvote this more than once! –  Chad Jul 13 at 2:48

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

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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
In Acrobat 9 Pro it's under the Document menu. –  svinto Jun 28 '13 at 13:15

Don't know it, but there is also comparePDF (not free, but a 30 day trial possible):

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I recently found this and I love it.

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):


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

\title{A brand new test}




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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
up vote 106 down vote

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

enter image description here

On Ubuntu install using:

sudo apt-get install diffpdf

See further this UbuntuGeek page on comparing pds textually or visually.

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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: Information about Windows build is here: 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 ( –  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

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
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%

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%
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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.

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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
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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)


wdiff <(pdftotext old.pdf -) <(pdftotext new.pdf -) | colordiff

Now I can see which words, nicely colored, have changed.

More details:


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:



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>

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

An example of output can be seen here

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