UPX

Input—per 1M tokens

Output—per 1M tokens

Context—tokens

WeightsClosed

About

UPX is ranked #4 of 27 in executable packers on Inferse. It runs on Linux, macOS, Windows. There is a free plan.

Compared on executable packers

Free plan: Yesupx.github.io
Supported platforms: Windows, macOS, Linuxupx.github.io
Binary formats: PE, ELF, Mach-O, COFF, DOS/COM, DOS/EXE, DOS/SYS, Atari/TOSupx.github.io
Compression levels: advancedupx.github.io
Protection features: Noupx.github.io
Architecture support: multi-architectureupx.github.io
License model: perpetualupx.github.io

Facts

Purpose: UPX is a portable executable packer and file compressor for several executable formats.upx.github.io · 30 Sept 2026
Compression: The project says UPX typically reduces program and DLL file sizes by around 50%–70%.upx.github.io · 30 Sept 2026
Runtime behavior: Compressed programs are self-contained and run as before with no runtime or memory penalty for most supported formats.upx.github.io · 30 Sept 2026
Supported executable formats: UPX supports formats including Windows programs and DLLs, macOS apps, and Linux executables.upx.github.io · 30 Sept 2026
Inspect and restore: UPX can list, test, and unpack executables, and internally maintains checksums of compressed and uncompressed files.upx.github.io · 30 Sept 2026
License: UPX is distributed with full source under GPL v2 or later, with a special exception allowing unmodified UPX to compress commercial programs.upx.github.io · 30 Sept 2026
Security handling: The project warns that UPX inherits the security context of files it handles and says to use it only on trusted files.github.com · 30 Sept 2026
Security limits: UPX describes itself as a packer and explicitly says it will not add protection or encryption features.github.com · 30 Sept 2026
Linux runtime tradeoff: The documentation says compressed Linux executables do not share RAM at runtime like file-mapped executables, so concurrent processes may need more RAM or swap.github.com · 30 Sept 2026
Linux temporary files: For its generic Linux format, UPX recreates a copy of the original file in /tmp before running it.github.com · 30 Sept 2026
Download platforms: The latest release page provides Linux and Windows binaries, DOS builds, and a source tarball; it says each build handles all supported executable formats.github.com · 30 Sept 2026
Support: The project asks users to report bugs through its GitHub issues page.github.com · 30 Sept 2026
Maker: The homepage says UPX is maintained by the UPX Team and credits Markus F.X.J. Oberhumer, László Molnár, and John F. Reiser.upx.github.io · 30 Sept 2026