xxdiff

About xxdiff

From Debian's package description

xxdiff is a powerful tool for viewing the differences between two or three files, or two directories, and can be used to produce a merged version. The texts of the two or three files are presented side by side with their differences highlighted with colors for easy identification. Among its features are:

• Compares two or three files, or two directories (shallow and recursive)
• Horizontal highlighting of diffs
• Interactive merges, previewing and saving of the resulting output
• Unmerges CVS conflicts and displays two files, to help resolve conflicts
• Fully customizable with a resource file
• Features and output that ease integration with scripts

The scripts that accompany xxdiff can be found in the xxdiff-scripts package.

From Debian's description of the xxdiff package, under that package's license.