A beautifier is a programmer's utility that reformats source code for compliance with a standard of presentation. The reformatting performed by a basic beautifier would include splitting long lines into shorter ones, adjusting the indentation step-size, and modifying indentation to properly reflect nesting levels. More elaborate beautifiers have options to align rows of initializers, align the opening and closing braces of code blocks, insert blank lines before and after subroutine definitions, insert a space between a function name and the opening parenthesis of its argument list, and so forth. For example, the GNU "indent" beautifier for the C language provides 51 separate user- selectable options, that provide for highly individualized definitions of beauty.

Beautifiers can enhance a program's readability, maintainability, and "debugability," and are generally considered essential utilities for high-level programming languages. So why doesn't Perl have one? One reason may be the widespread belief that writing a Perl beautifier would be a very difficult undertaking.