Free UPX – A Powerful Executable Packer

Free UPX - Screenshot 001

Free UPX is a free program  that lets you compress and decompress executable files.

Novice users might find its user interface and features a little overwhelming, but more-experienced users will find it to be a valuable compression tool. At first glance, Free UPX's user interface appears a little cluttered. But once I spent a little time with it,  I found it easy to navigate. Using the command buttons at the top of the window, I browsed for, and added, the executable files to be compressed. The layout of the interface flows really well, so we went easily from one step to the next, selecting the output file, compression type, and the force compression. My files were quickly compressed once  I gave it the go-ahead. Decompressing the files was just as easy;  I simply added the compressed file, went through the necessary steps, and selected the decompression option.

“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, because of in-place decompression.”


  • 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 edition-neutral C++.

  • Extendable: because of the class layout it's very easy to add new executable formats or new compression algorithms.
  • Optional LZMA compression.
  • Support for BSD systems.
  • 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.

           Supported executable formats:                                  

Free UPX - Supported executable formats - Screenshot 002


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OS Requirements:

Win 2000/Win 2003/Win Server 2008/

Win NT/Win XP/

Vista/Win 7Download - UPX

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Rating: 4.3/5 (2 votes cast)
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