MegaZip is a data compression and decompression utility developed for IBM Z mainframe environments running z/OS. It supports common compression formats including Gzip, ZIP, ZIP64, and TAR, enabling both single-file and multi-file compression and decompression operations. The tool is designed to reduce file sizes by up to 95%, which helps organizations decrease disk space consumption, lower bandwidth usage, and improve data transfer speeds. It operates natively within z/OS using an ISPF interface and sample executable JCL libraries, making it accessible to mainframe administrators familiar with standard z/OS tooling. MegaZip supports cross-platform compatibility, allowing compressed files to be transferred to and used on Windows, UNIX, and Linux systems. It also handles EBCDIC-to-ASCII text conversion, accommodating data interchange between z/OS and non-mainframe environments. A Blowfish encryption capability for z/OS and Windows is included with MegaZip at no additional cost, providing basic data security for compressed files. MegaZip is targeted at large enterprises and data centers operating IBM Z mainframe infrastructure that require reliable, high-ratio compression with cross-platform interoperability and integrated encryption.