The developer rig is a web app that will enable you to test an extension locally against production APIs across a variety of views and roles (e.g. the broadcaster live view). It also lets you quickly get started with Extensions by pulling down the new “Hello World” sample code, including a basic backend scaffold, and iterate on your extension so that you can completely focus on building a great experience for creators and viewers. You can also add additional views and customize the resolution to fit your development needs.
For more information, please see our blog post announcement.