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DiffPDF can compare two PDF files. It offers two comparison modes: Text and Appearance. DiffPDF is used to compare two PDF files—textually or visually, is developed by Mark Summerfield, he said “In theory DiffPDF could be built on Windows, but I haven’t managed to do it, so no Windows executable is available. The problem is that I don’t know how to build the Poppler library on Windows (apparently it isn’t easy!).” and I did some effort to compile to on windows.

By default the comparison is of the text on each pair of pages, but comparing the appearance of pages is also supported (for example, if a diagram is changed or if a paragraph is reformatted). It is also possible to compare particular pages or page ranges. For example, if there are two versions of a PDF file, one with pages 1-12 and the other with pages 1-13 because of an extra page having been added as page 4, they can be compared by specifying two page ranges, 1-12 for the first and 1-3, 5-13 for the second. This will make DiffPDF compare pages in the pairs (1, 1), (2, 2), (3, 3), (4, 5), (5, 6), and so on, to (12, 13).

A couple of example PDF files are provided (boson1.pdf and boson2.pdf) so that you can try it out. PDF files can be loaded from the GUI (by pressing the File #1 and File #2 buttons), or by specifying them on the command line. I use the tool regularly to compare different versions of my books (which are typically 500 or more pages), e.g., comparing a first printing with a second printing, to make sure that only the pages I intended to change have actually been changed.

DiffPDF is licensed under the GNU General Public License v 2 open source license. To build it you will need a modern C++ compiler, the Qt 4 libraries (at least Qt 4.4; 4.6 or later recommended), and the Poppler library—all these should be available as standard packages on most Linux and BSD systems. The source is diffpdf-1.8.0.tar.gz(40K). Building follows the standard pattern for Qt 4 applications and is explained in the README. Fedora, Debian, and Ubuntu users don’t have to build it manually, they can simply install the binary diffpdf package using their prefered package management tool—but make sure you get at least version 1.8.0!