Diff

Diff is a class of programming utilities that compares two or more files for changes or differences between them.

Diff as a file format

Although many newer diff tools have modified the output file format for more flexibility, the original diff output file format has become something of a standard since a number of utilities and systems can open up diff files for further processing or visualisation.

OS/2 text & programmers editors with diff file support

• Elvis - diff syntax support included by default - Open source - Current.