1. Martin Blais
  2. xxdiff



xxdiff: Graphical File And Directories Comparator And Merge Tool


This is the official home of xxdiff, a graphical file and directories comparator and merge tool.

xxdiff is provided under the GNU GPL open source license. It has reached stable state, and is known to run on many popular unices, including IRIX, Linux, Solaris, HP/UX, DEC Tru64. It has been deployed inside many large organizations and is being actively maintained by its author (Martin Blais).


  • Comparing two files, three files, or two directories (shallow and recursive);
  • Horizontal diffs highlighting;
  • Files can be merged interactively and resulting output visualized and saved;
  • Has features to assist in performing merge reviews/policing;
  • Can unmerge CVS conflicts in automatically merged file and display them as two files, to help resolve conflicts;
  • Uses external diff program to compute differences: works with GNU diff, SGI diff and ClearCase's cleardiff, and any other diff whose output is similar to those;
  • Fully customizable with a resource file;
  • Look-and-feel similar to Rudy Wortel's/SGI xdiff, it is desktop agnostic (i.e. will work equally well with KDE or Gnome);
  • Features and output that ease integration with scripts.

xxdiff was (and probably still is) tested daily in a merge reviewing/policing context by more than 50 engineers at discreet, and since this task is a significant part of their development process, many of the features are a direct result of suggestions from these people while the author was working there.

New releases and updates are announced on freshmeat. You can register for notification at either freshmeat or sourceforge. xxdiff is implemented in C++ and its runtime dependencies is only the Qt UI toolkit from TrollTech.

Unicode and Inline Editing

xxdiff does not support comparing files encoded with Unicode. Also, it does not support inline editing of the diffed files. If you need these features, you could try emacs or Meld (although both of these lack some of the most interesting features of xxdiff).



  • Source code can be found the public Mercurial repository, here:


  • Releases Download

  • A complete Qt4 port (which works on the Mac) has been done by Alexandre Feblot (alexandre dot feblot at gmail dot com). This forms the basis for versions 4.x of xxdiff as of November 2010. Some notes about the Mac OS X build:

    On OSX, a Qt bug (http://bugreports.qt.nokia.com/browse/QTBUG-9271) affects rendering performance. As a workaround you can use the much faster "raster" graphics engine by either

    • using the --graphicssystem raster option

    • defining this environment variable in your terminal:


    This engine has a couple of drawbacks (it will not refresh the display during window resizing, and will dump warning lines when opening native OSX dialogs like colors chooser or file selection dialogs), but it's worth coping with them anyway.

  • A recent Mac OS X binary build is available for download here:


  • An recent Windows 7 port of version 4.0 has been done by Rene J.V. Bertin (it's ifdef'ed).

  • An old Windows build for 2.9 (with some minor bugs) and based on the qt3 version can be found here:


    No support is offered though. Someone should probably port the newer qt4 code to Windows though, that would be worthwhile.


xxdiff comes with a bunch of wrapper Python scripts that invoke xxdiff in creative ways. The author has been using these for a long time now and decided for version 3.0 to clean them up and make them a little more generic so everyone can use them. As of version 3.2, the standalone scripts have been refactored a great deal, to share code together and to make them more stable. All this code is now distributed with xxdiff, in an xxdiff Python package, which you can leverage to build your own file transformation scripts around xxdiff.

See the document Helper Scripts for xxdiff for full details.

The scripts are available in the xxdiff distribution. To install them and the accompanying Python package, use the standard distutils procedure:

su -  # before root
cd xxdiff-3.x
python setup.py install

Other tools can be found in the distribution under the tools/ directory (CVS, ClearCase, etc.).


Packages are available for some specific operating systems. Here are links to the relevant pages. The author does not publish binaries anymore.

Reporting Bugs

PLEASE! report bugs using the bug tracker instead of email. It is extremely simple, quick and easy to use, you don't even have to have a SourceForge account, and it allows me to track issues and desired features, as well as keep a history and dates. Please do not send the author email about bugs. Log them, you don't even need a SourceForge account. Thank you.



Build dependencies are:

  • Qt-4.5 or higher
  • a C++ compiler, flex and yacc

Runtime dependencies are:

  • Qt-4.5 or higher


xxdiff is known to build and work on a great majority of UNIX platforms where Qt works, including Mac OS X.


Martin Blais <blais@furius.ca>

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