GUiPeX, pronounced "GWEE-pex" (see screenshot), is a name taken from GUI (Graphical User Interface) and UPX. UPX, a free DOS command-line tool, is a portable, extendable, high-performance executable packer for several different executable formats. It achieves an excellent compression ratio and offers very fast decompression. Your executable suffer no memory overhead or other drawbacks. Since UPX is a DOS tool, I thought I would write a simple GUI front-end for use in Windows. The primary use for GUiPeX is for software developers to compress their programs before distributing them to their customers or posting them on the internet. This makes the final file sizes much smaller (up to 75% smaller) for faster file transfers. However, anyone can use the tool to compress files on their systems to increase free disk space.