tkdiff

tkdiff is a graphical diff viewer based on the Tk framework.

[1] It is capable of inter-operating with source-control systems like CVS and Subversion to show the differences between the local copy and the repository version.

Such a line-by-line comparison is often considered to be good software engineering practice before committing code changes.

Tkdiff highlight specific differences within a line shared by both files, rather than simply indicating that the whole line differs.

tkdiff can also compare two older revisions of a file, etc.

tkdiff uses colors to suggest differences between files and within shared lines.