PDF Diff Tool

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Examine and visualize the differences between two PDFs in various creative ways.

This productivity tool solves the problem of comparing two PDF files with a creative touch — the two files can be compared in several different ways, as shown in the screenshot below — the ability to compare parsed texts is also seen elsewhere, however composition and content differences are something truly unique. This is the suitable as a diff-tool for developers who create PDFs and want to compare their day to day development output. You can explore the various types of information in an interactive way, or click the button “Report” to get an HTML output of full Diff results for every pages in both inputs.


What’s New?

The current version is 1.1. Compared to first release, it now supports the following features:

  • Cancellable reading and differencing operations.
  • Improved progress feedback in various forms.
  • New page-by-page image comparison.
  • New document structure comparison.
  • Various adjustments to GUI and usability.

The following shows the start up page for comparing document properties, featuring tree branch symbols for better viewing.



Basic Usage

Usage Tips
  • Drag and drop two files into the window for comparison.
  • Double-click an item will launch detailed word-diffs.
  • Double-click a changed page area to see details in contents.
  • REPORT button is in the title bar on top right.
  • INFO button shows the About box, where you should migrate to the last page to see the box to paste registration code.

There are two buttons on top; each is used to load one PDF file on each side. The design is straightforward and minimal. Many operations are so intuitive that it is just there when you need it — drop a file to the left side of the form, and it will appear as file A; drop it to the right side of the form, it will be file B. Drop two files into the form, and they are loaded on these two sides, older version to the left and newer to the right.

The idea is that the left hand side is considered an older version, the right side newer. The changed parts are marked in violet, where parts missing from right side are considered deleted from source, marked in orange red; new contents are considered insertion and marked in green. The color coding scheme is used throughout, in various forms. For example, each side is accompanied by a vertical bar showing you a glance of where the changes are throughout the entire range.

Within each changed line, further comparison is done to highlight the modified characters. If you double-click the line to show them in a pop-up window, you will get word-based differences instead.

A progress bar is displayed when the pages in the files are being read (stage 1), and when the differencing operation is being conducted (stage 2). There is a cancel button to interrupt either stage to avoid overconsumption of CPU resources. Sometimes there’s a circular progress dial to show that an operation is ongoing but the percentage is not possible to know.


Synchronized Scrolling

The two sides are synchronized, and this also applies to visual comparison. Drag on any of the two scroll bars to move up and down in the list. Also, you can use the up and down arrows to move to previous and next change locations. What you are seeing is in fact real-time rendering of page content and it is zoomable using vertical slide bar.


Compact View

The button with a target icon (at the bottom center) is used to show changes only. Press again to return to normal view. You will notice some items come with little icons, some with order numbers or unique id numbers, and some do not have anything. That’s dependent on the nature of the comparison method.


Item Diff View

Select one item on both sides, and click on the target button (between the two arrows), you will be able to further explore the differences between the two items. Normally each will be treated as a series of words, however, in the case of object comparison, you will be seeing actual object data.


Data Comparison

When files are first loaded, the PDF Diff Tool shows you the differences between the summaries of both files, with information on document Properties, encryption, font and image usage, etc. If you switch to Textual view, you see the pure text extracted from the entire document, optimized for line-based reading and comparison.

Data Copying

Look at the top right corner of the item diff box, and you can see a small button with caption “COPY”. That is used to copy the diff results as colorful HTML table data, so that you can either paste in Word or Excel, an email message, a web forum post, etc.

In the main window, when you select one or more items from both sides, and click the clipboard button, everything in-between will be copied in the same fashion.

Page Comparison

The other three types of diffing methods works on individual pages, thus you will be seeing a slide bar to page selection, if the number of different pages is greater than one. Note the word “total” — if file A has 3 pages, say a, b, d, and file B has 3 pages but a, c, d, then the slide bar will have four stops. You will notice that the stops may be colored in one of the three aforementioned colors to show you whether a page is changed, dropped, or added.

Synchronized scroll is evident in the Visuals view, too. In addition, you can zoom the views using the vertical slide bar. In compact view, the page content is largely invisible, leaving only those changed parts. Again, the regions are marked in different colors on the shown pages.


Contents and Composition

By Composition we refer to the content of each page in original PDF commands, while Contents refers to the actual text, image, or vector content items generated due to those commands. That is, one is text diff and the other is object diff. In the composition diff view, it will show you changes in text string.

In the visual diff view, double-click on any of the marked regions will show you the item diffs in a pop-up window, listing the properties of the item such as text, font, color, etc.


* Most downloads are packed in ZIP or RAR format. If you don’t have a decompressor, you can download one first from RarLab, maker of WinRAR.

About the Author: Cyphia