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Ultimate Executable Packer

UPX (Ultimate Executable Packer) 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 executables suffer no memory overhead or other drawbacks. UPX supports 32-bit and 64-bit GNU/Linux binaries, 32-bit Windows binaries and much more. Experimental support for 64-bit Windows binaries is also available.



Verified by

Verified on


Verified by


Verified on

31 July 2015


The exception allows using UPX in proprietary software, as long as UPX itself isn't modified. GPL-compatible programs are not affected by this restriction on modification.

Leaders and contributors

Markus F.X.J. Oberhumer Maintainer

Resources and communication

AudienceResource typeURI
Bug Tracking,Developer,SupportE-mailmailto:markus@oberhumer.com

Software prerequisites

Required to useUCL


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The copyright and license notices on this page only apply to the text on this page. Any software or copyright-licenses or other similar notices described in this text has its own copyright notice and license, which can usually be found in the distribution or license text itself.