mruby and mruby-cli makes it possible to ship single binary command-line tools that can be used without setup effort, but how difficult is development in MRuby? In this talk we'll explore how to work with MRuby and mruby-cli. We'll cover the differences in development patterns when using MRuby, the maturity of the MRuby ecosystem, and development patterns when using mruby-cli to build a command-line tool.