Let me introduce you to z/OS, a widely used mainframe operating system that is known for its security, reliability, and high performance. It is used in a variety of industries, including finance, healthcare, and government. In this talk, We'll embark on a journey to discover how to develop cutting-edge applications on z/OS with examples of how we enhanced z/OS by porting widely used development tools like Git, Bash, VIM and GNU Make to the platform. And in the process, we'll unlock the true power of the mainframe as a modern development platform. You'll learn about the unique challenges of working on a mainframe. We'll also explore the importance of encoding and endianness when developing and porting software to z/OS. We'll also uncover the hidden gems of the mainframe. We'll discover the unparalleled security, reliability, and high-performance features that make it a valuable platform for developing modern applications.