Free UPX is a specialized graphics overlay for the popular UPX compressor. The program enables compression and decompression of executable files compliant with Microsoft Portable Executable and COFF Specification (most of the EXE, DLL, OCX, BPL, CPL files). From the graphical interface, the user has access to all UPX parameters, even undocumented ones.

The basic operation of the program is very simple - just drag the desired file onto the program window, select the right profile from the list and press the Compress (or Decompress) button. Free UPX comes with the latest stable version of the UPX compressor available at the time of writing.