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UPX 4.0.1 – Ultimate Packer for eXecutables

UPX (Extreme Packer for eXecutables) is a free, compact, extendable, superior exhibition executable packer for a few different executable organizations.

It accomplishes a superb pressure proportion and offers extremely quick decompression. Your executables experience no memory above or different disadvantages for the majority of the arrangements upheld, due to set-up decompression.

UPX is protected programming conveyed under the details of the GNU Overall population Permit. Furthermore, with unique special cases conceding the free use for business programs as expressed in the UPX Permit Understanding.

This application involves the NRV pressure library for pressure administrations. A viable however to some degree less productive OpenSource execution is accessible through the UCL pressure library.

UPX Features:
  • Excellent compression ratio: typically compresses better than WinZip, Zip, and 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 files is maintained internally.
  • Universal: can pack several 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: 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 License Agreement.

Changes in version 4.0.0 (28 Oct 2022):
  • Switch to semantic versioning
  • SECURITY NOTES: emphasize the security context in the docs
  • Support easy building from source code with CMake
  • Support easy rebuilding the stubs from source with Podman/Docker
  • Add integrated doctest C++ testing framework
  • Add support for EFI files (PE x86; Kornel Pal)
  • bug fixes – see
  • bug fixes – see


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