UPX

UPX is a free, open-source executable packer that efficiently compresses Windows EXE and DLL files, significantly reducing their size without compromising functionality. It works by securely packing the binary, which decompresses in memory at runtime, ensuring the original program runs exactly as intended. This makes software distribution faster and saves storage and bandwidth. Trusted by developers for its reliability and lossless compression, UPX supports a wide range of executable formats and is command-line driven for easy integration into build processes.