Bare Bones Software, Inc.

A powerful text transformer and manipulator, featuring comprehensive AppleScript support, fast multi-file searching and replacing, PCRE (Perl-Compatible Regular Expression) text pattern matching, a rich plug-in architecture, and an array of text transformations to make sense of even the largest bodies of text.

This example shows TextWrangler's Find & Replace in action. Using a Regular Expression, we are transforming a last name, first name list to a first name last name list. (click the image above to see it full size in a new browser window)