UPX is a lightweight compression utility that you can use to pack several executable formats, including applications, DLLs, DOS programs and Linux executables.
This is portable software, so installation is not necessary; it means that you can run the tool directly from your removable drive.
One disadvantage of the program is that it can only be run using the command console. Thus, while for some it may seem easy to use, those who are not familiar to the console might find it a bit difficult.
Once you run the program, the usage syntax appears, as well as the available commands and the options to choose from. The syntax is simple, as you only have to write the UPX file path, the compression command, followed by the desired options and the output file name. You can choose fast compression or optimal one, as well as decompress files with the help of this utility.
Verbose and quiet compression are also included in the compression preferences. Moreover, you can force the compression of suspicious files and change the appearance of the command console, by removing colors and disabling the progress bar.
Detailed help is also available, in order to help you use the program at its full potential. Thus, accessing the help section reveals a set of extra options that do not initially appear. For example, opting for the 'Brute' or 'Ultra-brute' compression makes the program try several methods for compressing the files.
Also, you can back up the compressed files, as well as configure the overlaying actions and the output options. As an example, the application enables you to strip relocations and choose the number of icons to compress.
Although it is a command line application, UPX is a handy and reliable tool for compressing and decompressing files.