Apps Related to Customizable Output

K2PDFOPT is a command-line and GUI-based tool designed to optimize and reformat PDF and DJVU files, making them highly readable on mobile e-readers and tablets. It intelligently reflows text, removes white space, and improves image quality for a better reading experience on small screens.

Gnuplot is a portable, command-line driven graphing utility for interactive and non-interactive use. It can generate various plots of functions, data, and data fits in two and three dimensions. Widely used in scientific settings, it supports numerous output formats.

youtube-dl is a versatile command-line program designed for downloading videos from YouTube and a multitude of other video hosting websites. It supports downloading individual videos, entire playlists, and even extracting audio.