This application is well designed and saves me hours per week, so it's definitely worth the purchase price.


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PDF Comparator 3!


PDF Comparator 3 is a major upgrade to our popular PDF comparison application that uses Mac OS X’s built-in PDF rendering functionality to compare two PDFs to each other based on how they render and print, not just on their raw text or image content.

The screenshots below show a typical PDF Comparator display of two PDF pages and the differences between them. Hover over each of the three rectangular areas to see magnified views.


PDF Comparator 3 has all the functionality of of version 2:

  • Accurate display of each PDF page spearately, along with a view of any differences detected between them
  • Extensive control of rasterization parameters, including resolution, sensitivity, PDF “box” area to compare, etc.
  • The ability to open up to three windows to view a pair of pages, with or without synchronized sizing, zooming, and scrolling
  • Background checking of all pages in a pair of documents while viewing individual page comparisons in the foreground

PLUS, the PDF Comparator 3 Standard version has these new features and improvements:

  • Improved performance
  • Enhanced PDF page alignment

AND, on top of that, the Professional version of PDF Comparator 3 adds all of these features (most of them developed based on the great suggestions we’ve received from our version 2 users and version 3 beta testers):

  • Save and load comparison settings for later re-use
  • Turn on the new ‘Highlight Differences’ feature to avoid missing very small, though possibly significant, differences
  • Export comparison results to a PDF file
  • View PDF comments/annotations
  • Adjust the scaling of one PDF relative to the other
  • Set both X- and Y-offsets as well as scaling, with just a few mouse clicks
  • Use the ‘Loupe’ tool to magnify the area under the mouse cursor for more detailed examination without zooming the entire page display
  • Use the ‘Reduce Jitter’ function to minimize the effect of slight movement of text and small objects on the page
  • View raw text content of both pages, and the differences between them

Download the current release version of PDF Comparator using one of the links on this page. Without a valid license key, it will operate in “demo” mode in which half of each displayed PDF page will be obscured by a solid triangular area. If you’d like to try out PDF Comparator without this demo restriction, please contact us to receive a temporary license key.


Click here to download PDF Comparator

Click here to watch a brief overview movie.

Frequently Asked Questions (and answers)

Why do I need PDF Comparator if I already have Adobe® Acrobat® Professional?

While it is true that Acrobat Professional software has a “Compare Documents” feature, we feel that PDF Comparator is superior in several ways:

  • PDF Comparator displays differences in a way that is much easier to understand and manage. Because Acrobat creates an individual note object for each difference it finds, making sense of the findings can be a daunting task, especially on pages which contain many differences.
  • PDF Comparator gives the user more control of the comparison parameters than Acrobat does.
  • PDF Comparator detects some differences that Acrobat misses.
  • PDF Comparator is significantly faster in our testing.

Why is PDF Comparator only available for Mac OS X?

We've designed PDF Comparator to use Mac OS X’s built-in capability to render PDFs. Since no other OS has this built-in capability, we have so far only created a Mac OS X version of PDF Comparator. There are other implementation options, such as using third-party RIPs or using a “helper app” such as Adobe Photoshop®. While these alternatives may carry with them either cost or performance penalties, we will consider them for future development if there is enough interest for versions on other operating systems.

What are the known issues or limitations of PDF Comparator?

As with all software, PDF Comparator has a few known issues and limitations you need to be aware of. Because it relies on the operating system to render the PDFs being compared, it is subject to the same limitations as other apps that do the same. In general, PDF Comparator will “see” your PDFs exactly as the Finder,, or would. This means that certain things may be problematic:

  • Certain transparency effects may not be rendered correctly.
  • Overprint attributes will not be honored.
  • PDF Comparator cannot detect the differences between color spaces (e.g., 0R-0G-0B will not be distinguished from 0C-0M-0Y-100K).


Mac and Mac OS are registered trademarks of Apple Inc. • Adobe, Acrobat, and Adobe Photoshop are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and/or other countries.