Fldiff is a graphical diff program that shows the differences between two files/directories, or a file/directory and a CVS or Subversion repository. It is inspired by xdiff (Motif-based) and xxdiff (Qt-based), whose choice of GUI toolkit has hampered their portability to many of the systems.

Fldiff uses the Fast Light Toolkit (FLTK) and has been tested on AIX, IRIX, Linux, MacOS X, and Solaris, and should also run on Windows.