Mobile test automation is becoming increasingly important. Appium is a test automation framework that can test mobile web, mobile native and mobile hybrid applications on iOS and Android. We have used this in multiple projects and have seen significant gains. At the core, Appium is a webserver that exposes a REST API, receiving connections from a client, listening for commands, executing those commands on a mobile device and responding with an HTTP response representing the result of the command execution. It allows tests to be written against iOS and Android using the same API. Appium is open source with easy setup using npm.