The final version was entirely written by Douglas McIlroy.

The diff utility was developed in the early 1970s on the Unix operating system. The output is called a 'diff', or a patch since the output can be applied with the Unix program patch. Modern implementations also support binary files.

It is used to show the changes between two versions of the same file. It displays the changes made in a standard format, such that both humans and machines can understand the changes and apply them: given one file and the changes, the other file can be created. The diff utility is a data comparison tool that calculates and displays the differences between two files.

You can choose whether you want to see the difference between two given texts by characters, words or lines. It will graphically show you the differences between the 2 textareas by highlighting those changed areas in red color. Using the tool is super easy input the two texts in separate boxes and you can see the output right below.

This tool provides an easy way to highlight the differences between the two inputted texts. Use this online free Code Diff Tool for comparing two text files.

Online code writing tool