Many projects rely on command-line tools to provide an efficient and powerful interface to work. Building tools for everyone can be difficult, because of conflicting environment or OS. How can we build command-line apps that work for everyone and still write Ruby? This talk will discuss how to use mruby-cli to build cross-platform apps in Ruby. Our goal will be to build a CLI app using mruby and produce a self-contained binary that can be shipped to end users. Since mruby is designed to be embedded and statically compiled, it's also really good at packaging ruby code.