What is “upx” Package?

Compress/expand executable files. UPX is a portable, extendable, high-performance executable packer for several different executable formats. It achieves an excellent compression ratio and offers *very* fast decompression. UPX achieves an excellent compression ratio and offers very fast decompression.
For more details: https://upx.github.io/

Installation

• Open Terminal by pressing command+space then type terminal and hit Enter key.
• Install homebrew first.

  ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null

• Install upx.

  brew install upx

Now, use upx!

UPX strengths in a nutshell:

• 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 endian-neutral C++.
• extendable: because of the class layout it’s very easy to add new executable formats or new compression algorithms.
• 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.