UPX is a free, portable, extendable, high-performance executable packer for several executable formats.
UPX achieves an excellent compression ratio and offers very fast decompression. Your executables suffer no memory overhead or other drawbacks for most of the formats supported (including programs and DLLs, DOS programs, and Linux executables), because of in-place decompression.[ Key Features ]
Excellent compression ratio: typically compresses better than WinZip/zip/gzip, use UPX to decrease the size of your distribution!
Very fast decompression: ~10 MB/sec on an ancient Pentium 133, ~200 MB/sec on an Athlon XP 2000+.
No memory overhead for your compressed executables because of in-place decompression.
Safe: you can list, test and unpack your executables. Also, a checksum of both the compressed and uncompressed file is maintained internally.
Universal: UPX can pack a number of executable formats.
Portable: UPX is written in portable endian-neutral C++.
Extendable: because of the class layout it's very easy to add new executable formats or new compression algorithms.
Free: UPX is distributed with full source code under the GNU General Public License v2+, with special exceptions granting the free usage for commercial programs as stated in the UPX License Agreement.
You probably understand now why we call UPX the "Ultimate Packer for eXecutables". UPX aims to be commercial quality free software, based on experience with our previous packers (DJP, lzop, and the NRV library).[ Supported Formats ]
ARM/PE[ Edition Statement ]
Atari TOS/MiNT executable
DOS 16-bit .com file
DOS 16-bit executable
DOS 16-bit .sys file
DOS 32-bit COFF
DOS 32-bit executable
DOS 32-bit linear executable
Linux/ELF on i386, x86-64, ARM, PowerPC
Linux/kernel on i386, x86-64 and ARM
PlayStation 1 executable
Win32/PE (excluding files built using the .NET Framework)
Windows 32-bit executable or DLL
Windows CE executable or DLL
Mac OS X executable
This is the DOS Version (that means you need to operate it in the command line–"Run / CMD")![ Related Link ]UPX Forums[ Official Download ]