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DiffPDF Changelog

What's new in DiffPDF 6.1.0

Feb 15, 2024
  • Switched to annual license keys only. These are not tied to the hardware and may be transferred (moved) freely from one computer to another. These licenses can be purchased singly. (Existing “full” license keys continue to work normally.) Click Help→About to see which kind of license is in use and when it expires.
  • License changes.

New in DiffPDF 6.0.8 (Jan 30, 2024)

  • License changes.

New in DiffPDF 6.0.7 (Nov 15, 2023)

  • We strongly recommend setting the number of cores DiffPDF uses to the number of cores in your CPU, since doing so may provide a considerable speedup if the automatic core detection has underestimated. See the manual's “Improving Comparison Speed” section.
  • Library updates.
  • License changes.

New in DiffPDF 6.0.6 (Mar 7, 2023)

  • The Register Copy button has been reenabled. The problem is due to a Windows clipboard reliability issue. If copying the Computer ID fails, open C:Users<username>cid.txt in Notepad and copy it from there.
  • Minor internal improvements and library updates.

New in DiffPDF 6.0.5 (Jan 23, 2023)

  • The Register Copy button has been disabled since it doesn't currently work. To copy the Computer ID to register a license key, either type it manually, or better still copy it from the file C:Users<username>AppDataLocalTempcid.txt.
  • Dragging and dropping files no longer works reliably so has been dropped.

New in DiffPDF 6.0.4 (Jan 18, 2023)

  • This version is significantly faster on Windows 10 than on Windows 7.
  • Minor internal improvements, library updates, and a tiny error-message-related bug fix.

New in DiffPDF 6.0.3 (Dec 3, 2022)

  • Minor internal improvements and library updates.

New in DiffPDF 6.0.2 (Sep 23, 2022)

  • Various minor internal improvements and library updates. These should make some comparisons slightly faster.

New in DiffPDF 6.0.1 (Sep 21, 2021)

  • Various minor internal improvements and library updates. These should make word-mode comparisons slightly faster in some cases.

New in DiffPDF 6.0.0 (Jul 6, 2020)

  • Added support for high quality PDF report output. Version 5 produced its PDF reports by “photographing” pages from the original PDFs. Version 6 copies the actual pages from the original PDFs. This is faster and means that if the original pages are scalable, then the report will scale too, i.e., you can zoom in as much as you like on the report PDF and it will always be clear and sharp.
  • Various minor internal improvements and library updates.

New in DiffPDF 5.9.5 (Mar 19, 2020)

  • Added support for doing appearance mode comparisons with the “new” renderer. In some rare cases the “old” renderer doesn't detect some gradient fill differences—but the new renderer does.

New in DiffPDF 5.9.4 (Dec 5, 2019)

  • Updated libraries, including the PDF library.

New in DiffPDF 5.9.3 (Oct 15, 2019)

  • The first time DiffPDF is run it will automatically attempt to acquire a free trial license key over the internet and be ready for use immediately. (This means that the very first startup may take slightly longer than normal.)
  • Updated some libraries.

New in DiffPDF 5.9.2 (Apr 14, 2019)

  • Usability improvement: if you ask for a PDF report, when the report is ready you are offered the option to view it in your PDF reader.
  • Updated libraries to make DiffPDF slightly faster and use less memory.
  • Log files (which were normally empty) are no longer created.
  • Updated and clarified the license.

New in DiffPDF 5.9.1 (Jan 8, 2019)

  • Updated some libraries (bug fixes and a tiny speed improvement).
  • Updated the license.

New in DiffPDF 5.9.0 (Nov 13, 2018)

  • Updated to use a new PDF library that supports the new PDF 2 standard, in addition to the existing PDF 1.x standards that previous versions support. In many use cases the new library uses less memory and is faster.

New in DiffPDF 5.8.3 (Apr 17, 2018)

  • This version will work with free trial and full licenses as usual, and in addition will work with site licenses.

New in DiffPDF 5.8.2 (Apr 12, 2018)

  • A new .csv report format can be chosen by checking the Report option's New CSV Format checkbox. This is more robust than the old format and is compatible with new product developments.
  • Acquiring a free trial key should be a tiny bit easier since DiffPDF now attempts to pre-fill-in the Computer ID.

New in DiffPDF 5.8.1 (Mar 17, 2018)

  • Optimizations have been applied to the Standard text comparison algorithm which produce noticable speedups in many cases. (The most important optimizations are only available in 64-bit editions. These editions can run more than 10% faster—depending on the PDFs being compared—at the expense of using more memory.)

New in DiffPDF 5.8.0 (Feb 14, 2018)

  • Optimizations have been applied to the Standard text comparison algorithm which produce noticable speedups in many cases. (The most important optimizations are only available in 64-bit editions. These editions can run more than 10% faster—depending on the PDFs being compared—at the expense of using more memory.)

New in DiffPDF 5.7.0 (Jan 19, 2018)

  • Replaced the options tabs with an easier-to-use combobox plus options panels combination. This also takes up much less vertical space.

New in DiffPDF 5.6.8 (Nov 6, 2017)

  • Added a new Ignore Hyphens checkbox in the Text Modes tab. This defaults to unchecked. If you check it hyphens will be ignored. This means that, for example, one–two is treated as onetwo. This works even if two is on the next line.
  • PDFs (and therefore reports) can now be zoomed up to 800%. (The previous limit was 400%.) Zooming takes more memory and CPU time, e.g., 200% takes 4x the memory and CPU, and 400% takes 16x the memory and CPU, so zooming beyond 400% is best used only on a high performance computer with plenty of RAM and using a 64-bit version of DiffPDF.

New in DiffPDF 5.6.7 (Apr 3, 2017)

  • Updated—and slightly faster—PDF library.

New in DiffPDF 5.6.6 (Feb 24, 2017)

  • Improved PDF report output to use Portrait/Landscape more appropriately when outputting the changes for only one of the two PDFs.
  • Tiny minor internal improvements.

New in DiffPDF 5.6.5 (Jan 6, 2017)

  • For report types that have titles, the title now shows each PDF's filename with its full absolute path (previously the absolute or relative path was shown).
  • Added a new Path in Title checkbox to the Reports tab. This is checked by default in which case DiffPDF has the same behavior as previous versions, but which if unchecked will mean that report titles contain filenames without paths.
  • Added a new Compare Zoomed checkbox to the Appearance Mode tab. (This is only needed in very rare cases as explained in the manual.)
  • Improved error logging.
  • Various internal improvements.
  • Updated some of the libraries that DiffPDF uses.

New in DiffPDF 5.6.4 (Jul 8, 2016)

  • Fixed a bug which caused missing pages to always be the size of the first page rather than of the corresponding page. This only affects PDFs which have different numbers of different-sized pages.
  • Updated the PDF library. This improves rendering and accuracy in some quite rare cases.

New in DiffPDF 5.6.3 (Feb 17, 2016)

  • Added an Always Compare Afresh checkbox—default unchecked—to the Application tab. If checked, DiffPDF will not cache its results, and will perform every comparison from scratch. This is useful if one or both PDFs is being changed between comparisons.
  • Allow the zoom to go up to 400%—this is fine (although maybe slow) for viewing, but is not recommended for PDF reports as it would make them extremely slow to produce. (For reporting, the zoom is best set to 100% or 150%.)
  • Updated the PDF library. This improves rendering and accuracy in some very rare corner cases. Also, the library is slightly faster.

New in DiffPDF 5.6.2 (Jan 22, 2016)

  • The Swap button now not only swaps the two PDFs, but also their Pages.
  • The Application tab's Save Memory checkbox now defaults to being unchecked. We recommend unchecking the Save Memory checkbox unless you are comparing large (1,000+ page) PDFs and need to save memory.
  • Updated the About box and License to ensure LGPL compliance.

New in DiffPDF 5.6.1 (Nov 26, 2015)

  • Added a new Save Memory checkbox to the Application tab that is checked by default. If unchecked (and after DiffPDF has been restarted), some rare PDFs that could not be rendered before (and therefore could not be compared), will now be able to be rendered and compared—at the cost of using a lot more memory.

New in DiffPDF 5.6.0 (Nov 25, 2015)

  • Password-protected PDFs should now be comparable again (providing you enter the correct password).

New in DiffPDF 5.5.2 (Nov 12, 2015)

  • Fixed bug that prevented the change bar from being switched off, and now correctly remember whether the bar is on or off between sessions.

New in DiffPDF 5.5.1 (Nov 12, 2015)

  • Added a new Report PDF Changes checkbox that if checked will cause DiffPDF to watch the PDFs and report if they are changed in the status area.
  • Minor bug fixes and improvements.

New in DiffPDF 5.5.0 (Nov 12, 2015)

  • Added a new “Multi-Column” comparison algorithm that can produce much better results for multi-column PDFs than the Standard algorithm. The comparison algorithm is set in the Text Modes tab.
  • A new Column Tolerance option is available in addition to the existing Line Tolerance option—both of these are set in the Text Modes tab, and either or both can be used to tweak the Multi-Column algorithm's behavior.
  • Added a new Normalize Ligatures checkbox in the Text Modes tab. The default is unchecked (the current behavior). If checked, ligatures are treated as if spelled out, e.g., ? = fi, ? = fl, etc.
  • DiffPDF is now available as a 32-bit or a 64-bit application. The 32-bit version will work on 32-bit and 64-bit Windows, whereas the 64-bit version will work only on 64-bit Windows. The advantage of the 64-bit version is that it does not have the 2GB memory limit that 32-bit applications have. This makes it possible to compare huge PDFs using Appearance mode—providing the machine has enough free memory.
  • Comparisons now use less memory—considerably less when using Appearance mode.
  • Numerous minor improvements.

New in DiffPDF 5.3.1 (Jul 22, 2015)

  • The license has changed to allow for a license key to be reissued at most once, within one year of purchase. In effect this allows a key to be transferred if a computer breaks or is replaced.

New in DiffPDF 5.3.0 (Jun 25, 2015)

  • The Computer ID used for license keys is now based on the CPU and Motherboard only, and is no longer dependent on the BIOS. This means that license keys issued on and from 2015-06-26 for version 5.3.0 and later will not be affected by BIOS changes. Old license keys will continue to work (providing the BIOS, CPU, and Motherboard are unchanged).

New in DiffPDF 5.2.1 (Jun 5, 2015)

  • Comparisons are now faster in many cases.
  • It is now possible to set up to 20 rectangles to exclude (the limit in previous versions was 5).
  • Clicking the PDF views will only set corners, margins, or rectangles if the Show Options checkbox is checked—this is to avoid setting them accidentally.
  • Updated some of the libraries used by DiffPDF. This should ensure that some very rare PDFs that couldn't previously be rendered are now rendered correctly

New in DiffPDF 5.2.0 (Apr 27, 2015)

  • Eliminated some rare false positives.
  • Fixed a bug in page range handling that caused problems in some rare cases.
  • Increased the pairs limit (how many pairs of pages can be compared as if one very long page) from 1,000 to 5,000. Setting pairs to 1 (the default) and using page ranges is still to be preferred.
  • Subtle user interface bug fixes to ensure that comparisons are redone when appearance comparison settings are changed.
  • Small and subtle user interface improvements, including new icons.
  • Updated some of the libraries used by DiffPDF.

New in DiffPDF 5.1.2 (Mar 26, 2015)

  • Added a Copy Exclusions button to the Application tab: click this to copy the excluded corners, margins, and rectangles to the clipboard in .dpc format ready to be pasted into a DiffPDFc .dpc configuration file.
  • Updated some of the libraries used by DiffPDF.

New in DiffPDF 5.1.1 (Mar 4, 2015)

  • Bug fix: rectangle color and style are now correctly applied.

New in DiffPDF 5.1.0 (Mar 4, 2015)

  • Added support for arbitrary rectangle exclusion (in addition to the existing support for margin and corner exclusion). This means that any arbitrary rectangles anywhere on the page can be excluded from comparisons.
  • Corners and margins exculsions now use whole numbers of points to be consistent with rectangle exclusions.
  • Appearance accuracy now uses whole number percentages.
  • By default the Control Panel always appears on the left of the window, with the two PDF View Panels in the middle and right. It is now possible to choose any one of four window layouts in the Application tab.
  • It is now possible to set the “Missing Page” text to any text you like in the Appearance tab's Missing Page Text line edit.

New in DiffPDF 5.0.0 (Mar 4, 2015)

  • Added the Accuracy option in the Appearance settings tab. By default appearance mode comparisons compare every corresponding square exactly, pixel for pixel, i.e., comparison accuracy is 100%. In some situations it is useful to consider pages that are almost identical to be the same—this can now be done by setting the accuracy to less than 100% (e.g., to 99% or less).
  • Added support for remote deployment (i.e., bypassing the Register window and avoiding the need to use the .msi installer on individual computers), for customers who buy at least ten licenses.
  • Unlike version 4.x, password-protected PDFs cannot be compared. We hope to reinstate this functionality in a later 5.x release.
  • Implemented a new license key scheme, and updated the license terms to match.
  • It should now be possible to compare huge PDFs (those with thousands or even tens of thousands of pages).
  • Improved the comparison speed. For PDFs in the tens of pages the improvement could be 5% or more; for PDFs in the hundreds of pages the improvement could be 30% or more, and for thousand page plus PDFs the improvement could be 40% or more.
  • Reduced memory consumption by up to 50% for large PDFs.

New in DiffPDF 4.1.6 (Mar 4, 2015)

  • In some rare cases a valid license key could wrongly be identified as invalid: this has now been fixed.

New in DiffPDF 4.1.5 (Nov 7, 2014)

  • Reintroduced the .log report type since some customers are using it.

New in DiffPDF 4.1.4 (Nov 7, 2014)

  • Bug fix. If the number of cores cannot be detected the program defaults to 1 (before it silently failed). This can be overridden by checking the Show Options checkbox, clicking the Application tab, and setting the Cores spinbox to the actual number of cores the computer has.
  • Dropped the .log report type.

New in DiffPDF 4.1.3 (Nov 7, 2014)

  • The maximum square size is now 144 pt to allow for coarser-grained appearance comparisons.
  • The license key is more robust in the face of changing network configurations.

New in DiffPDF 4.1.2 (Nov 7, 2014)

  • Added .log report type that produces basic summary information.
  • Fixed a bug where PDF report pages got smaller and smaller.
  • Added a paragraph to the license clarifying use within virtual machines.
  • Changed all website and documentation links from diffpdf.appspot.com to www.qtrac.eu.

New in DiffPDF 4.1.1 (Nov 7, 2014)

  • Bug fix. In rare cases PDF reports could be missing a page; this has been fixed.
  • Now gives a percentage indication of approximately how different the PDFs are overall.
  • Tiny cosmetic change to the button layout.

New in DiffPDF 4.1.0 (Nov 7, 2014)

  • Improved speed—up to 10% faster for book-length documents.
  • Added a “Swap” button to make it easy to swap the left and right PDFs.
  • The page list view now gives a visual and percentage indication of approximately how different pages are.
  • Added indicators to the toolbox tabs to make it more obvious that they are clickable and whether they are “open”.
  • Improved the button arrangement.
  • Bug fixes. PDF filenames and page ranges can no longer be changed during a comparison.

New in DiffPDF 4.0.5 (Nov 7, 2014)

  • Subtle algorithm improvement which eliminates some rare false positives.
  • PDF report headers now end with the program name and version rather than just the program name.

New in DiffPDF 4.0.4 (Nov 7, 2014)

  • Bug fix. In rare cases margin exclusion didn't always work correctly in text modes—this has now been fixed.

New in DiffPDF 4.0.3 (Nov 7, 2014)

  • Bug fix. Whitespace is now fully normalized. This means that all whitespace characters (space, non-breaking space, etc.), are treated as a space (i.e., as a word separator)—this reduces false positives in some cases.

New in DiffPDF 4.0.2 (Nov 7, 2014)

  • Improved PDF library: this produces more accurate results, but can be slightly slower for book-length documents.
  • More attractive splitters.

New in DiffPDF 4.0.1 (Nov 7, 2014)

  • Startup is now much faster.
  • The line tolerance algorithm is now specified by name (Standard or Special) rather than by number.
  • Tiered price discounts are available when buying at least 10 licenses.
  • The About window now shows the computer ID. This is useful for identifying the computer for those who have bought multiple license keys.

New in DiffPDF 4.0.0 (Nov 7, 2014)

  • Added a Show Inserted/Deleted Pages text mode option. This can result in more understandable results in some cases when using a Pairs setting greater than one.
  • Changed how license keys work so that they are now tied to the computer DiffPDF runs on rather than to the licensee's name. The Register window has been updated to reflect this change.
  • Changed the license terms to match how the new license keys work.

New in DiffPDF 2.1.3 (Oct 23, 2013)

  • Minor GUI fixes.
  • Subtle bug fix by Bryan Huh which _may_ help resolve the bug that
  • affects saving when page ranges are in effect.

New in DiffPDF 2.1.2 (Jan 29, 2013)

  • Minor GUI bug fixes.
  • Minor translation fixes.
  • Updated copyright year.

New in DiffPDF 2.1.1 (Jan 29, 2013)

  • Tiny bug fix to make sure that the help file is in the right language.

New in DiffPDF 2.1.0 (Jan 29, 2013)

  • Dragging and and dropping files from Windows Explorer, Thunar, etc.,
  • now works (at least for me, on Windows 7 and Xubuntu).
  • Updated Czech translation.
  • French translation from Pierre-Alain Bandinelli.
  • German translation (and many suggestions) from Rainer Krachten.
  • Translations should "just work"; i.e., if you use a French locale then the user interface and help text should appear in French. However, you can force DiffPDF to use any language it supports by using the language command line option (e.g., --language=fr). If an unsupported locale or --language option is used, DiffPDF will fall back to English.
  • Now support -h as a synonym for --help.
  • Initial path defaults to home directory instead of DiffPDF's installation directory.
  • Improved the Options dialog's layout.
  • A subtle bugfix to the --words command line option.
  • Fixed a crash: clicking to set a margin when there're no PDFs loaded now safely does nothing.

New in DiffPDF 2.0.0 (May 4, 2012)

  • Can now have comparisons exclude text that's outside user-specified margins. This feature was sponsored by a company that prefers to remain anonymous
  • Save As can now save images as well as PDFs
  • Minor bug fixes and improvements
  • Command line help (--help) will no longer work on Windows. This is to avoid a spurious console window appearing. I've put the output in the online help though
  • Improved dock window handling so that docks can now be stacked on top of each other (useful for small screens)

New in DiffPDF 1.9.2 (May 4, 2012)

  • Added missing step to the README

New in DiffPDF 1.9.1 (May 4, 2012)

  • Save As now preserves the aspect ratio.

New in DiffPDF 1.9.0 (May 4, 2012)

  • Added Czech translation provided by Pavel Fric.
  • Will now use the default locale's language for standard dialogs (e.g.,
  • for the file dialog).
  • Dragging & dropping one or two files onto the filename line edits or
  • onto the file viewer panels is now supported. Independently suggested
  • by Liviu Andronic and Rory Gordon. (This does not seem to work on
  • Windows.)
  • Show Zones checkbox is always visible (it was only visible with
  • debug in earlier versions).
  • DiffPDF now starts up with its initial comparison mode being whatever
  • comparison mode was in force when it was shut down (or Words mode the
  • first time it is run).
  • Improved About box with more version info + contributors.
  • Added --help command line option. (For Windows this only works if
  • diffpdf is compiled with access to the console.)

New in DiffPDF 1.8.0 (Feb 14, 2012)

  • Introduced zoning: this can be slow in Characters mode but can provide better accuracy in text modes.

New in DiffPDF 1.7.1 (Feb 14, 2012)

  • Improved Character mode to be as liberal about hyphens as Words mode.
  • Minor doc changes that I forgot for 1.7.0.
  • Minor GUI bug fixes and changes.
  • Minor under the hood efficiency improvements.

New in DiffPDF 1.7.0 (Feb 14, 2012)

  • Renamed Text mode to Words mode. This mode is best for alphabetic text
  • (e.g., English).
  • Added Characters mode. This mode is best for logographic text (e.g., Chinese and Japanese).

New in DiffPDF 1.6.3 (Feb 14, 2012)

  • Very minor cosmetic changes.

New in DiffPDF 1.6.2 (Feb 14, 2012)

  • Save button is now only enabled if there are changes.
  • An improved help window with slightly more information.

New in DiffPDF 1.6.1 (Feb 14, 2012)

  • In rare cases the highlighting on the right hand page could be in the wrong (horizontal) position; this has now been fixed.

New in DiffPDF 1.6.0 (Dec 2, 2011)

  • In addition to Appearance comparisons using highlighting, they can now also some composition modes to help make subtle differences more visible. (This was inspired by feedback by Florian Heiderich.)
  • Can now control the square size for appearance comparisons. Using very small squares can help reveal tiny Appearance differences.
  • Can now control the fill opacity for highlighting.
  • Extended zoom range from 20% to 800% (was 25% to 400%).

New in DiffPDF 1.5.1 (Nov 23, 2011)

  • Quite a few false-positives have now been eliminated:
  • All hyphens are treated the same now.
  • Some weirdly-encoded open/close double-quotes are treated as normal
  • Unicode open/close double-quotes.
  • Improved whitespace ignoring.

New in DiffPDF 1.5.0 (Nov 23, 2011)

  • Added Save As action and dialog for saving the differences to a PDF file.

New in DiffPDF 1.3.0 (Nov 23, 2011)

  • Added support for -a, --appearance, -t, --text command line options to
  • set the initial comparison mode.

New in DiffPDF 1.2.3 (Nov 23, 2011)

  • Added a mention of comparepdf in the About box.

New in DiffPDF 1.2.2 (Jun 21, 2011)

  • Tiny change in how command line arguments are handled. This should make things work with both English and non-English locales on Windows.

New in DiffPDF 1.2.1 (Jun 21, 2011)

  • Minor improvement with focus control for Previous and Next buttons.

New in DiffPDF 1.2.0 (Apr 25, 2011)

  • Got rid of old text comparison mode.
  • Various small user interface improvements.
  • Fixed a subtle bug that meant the combine text highlighting setting wasn’t saved and restored correctly.

New in DiffPDF 1.1.5 (Apr 1, 2011)

  • Slightly changed the .pro file to make it a tiny bit more helpful.
  • Added a Help button and separated Help and About information.
  • Updated the README for Mac users (thanks to Dirk Loss for the info).

New in DiffPDF 1.1.4 (Apr 1, 2011)

  • Improved the reporting of files that are the same.

New in DiffPDF 1.1.2 (Apr 1, 2011)

  • It is now possible for the user to control whether highlighting is combined in text mode.
  • Added a cache for page images. This makes it much quicker to flick back and forth between pages. The cache size can be set by the user: the bigger the cache the more pages that can be flicked through without recalculating.

New in DiffPDF 1.1.1 (Apr 1, 2011)

  • Replaced QVariant::toReal() with QVariant::toDouble() to avoid breaking
  • compatibility with Qt 4.4.

New in DiffPDF 1.1.0 (Apr 1, 2011)

  • Added margin rules to indicate where changes are. (These can be turned off by setting a rule width of 0.0.)

New in DiffPDF 1.0.0 (Apr 1, 2011)

  • Implemented the sequence matcher algorithm for text mode matching.

New in DiffPDF 0.6.0 (Apr 1, 2011)

  • Redid the user interface to use dock widgets.