The Cast Application Framework (CAF) is a platform for developing and running multimedia applications on Chrome OS devices such as Chrome-books and Chromeboxes. CAF is based on the Chrome browser and provides a set of APIs and tools to create, test, and distribute applications that can run on Chrome OS.
CAF applications are written in HTML, CSS, and JavaScript and can access native device capabilities, such as audio and video playback, and system functions such as the file system and network communication. The framework provides a number of tools and libraries to help developers create rich and engaging applications, including a user interface library, a media player framework, and support for managing application state and lifecycle.
CAF is designed to be simple and lightweight, making it easy for developers to create applications that run well on Chrome OS devices. With CAF, developers can create applications that are fast, responsive, and secure, and can take advantage of the latest web technologies to provide a great user experience.
https://medium.com/google-developers/the-new-cast-application-framework-receiver-sdk-eca21853b888