The ups, the X (UPX stands for the Ultimate Packer for Executables) is a tool open source and free for packaging (Packing) files of the executive is that of the different formats on different platforms support.

UPX, using compression algorithm given the name of UCL, which is an implementation of open source algorithms NRV (abbreviation:Not Really Vanished) is used.< < - > .L and is designed so that the -y action can be implemented in just a few hundred bytes. U does not require any additional memory for decomp oession.