UPX: the Ultimate Packer for eXecutables - Homepage

UPX

the Ultimate Packer for eXecutables

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Welcome

UPX is a free, secure, portable, extendable, high-performance<br>executable packer for several executable formats.

Introduction

UPX is an advanced executable file compressor. UPX will typically<br>reduce the file size of programs and DLLs by around 50%-70%, thus<br>reducing disk space, network load times, download times and<br>other distribution and storage costs.

Programs and libraries compressed by UPX are completely self-contained<br>and run exactly as before, with no runtime or memory penalty for most<br>of the supported formats.

UPX supports a number of different executable formats, including<br>Windows programs and DLLs, macOS apps and Linux executables.

UPX is free software distributed under the term of the GNU General<br>Public License. Full source code is available.

UPX may be distributed and used freely, even with commercial applications.

Overview

UPX strengths in a nutshell:

secure : as UPX is documented Open Source since many years any relevant<br>Security/Antivirus software is able to peek inside UPX compressed apps to verify them

excellent compression ratio : typically compresses better than<br>Zip, use UPX to decrease the size of your distribution!

very fast decompression : more than 500 MB/sec on any reasonably modern<br>machine

no memory overhead for your compressed executables because of in-place<br>decompression

safe : you can list, test and unpack<br>your executables. Also, a checksum<br>of both the compressed and uncompressed file is maintained internally.

universal : UPX can pack a number of executable formats, including<br>Windows programs and DLLs, macOS apps and Linux executables

portable : UPX is written in portable endian-neutral C++

extendable : because of the class layout it's very easy to add new<br>executable formats or new compression algorithms

free : UPX is distributed with full source code under the terms of the<br>GNU General Public License v2+;<br>either under the pure GPLv2+, or (at your option) under the GPLv+2 with special<br>exceptions and restrictions granting the free usage for all binaries<br>including commercial programs as stated in the<br>UPX License Agreement

You probably understand now why we call UPX the "Ultimate Packer for eXecutables"

Copyright

UPX is Copyright &copy; 2024<br>by<br>Markus F.X.J. Oberhumer,<br>László Molnár &<br>John F. Reiser.

The term UPX is a shorthand for the<br>Ultimate Packer for eXecutables. All trademarks, brands, and names<br>are the property of their respective owners.