This document introduces the prototyping tool "Degino", which is powered by Ext JS and Google App Engine. It allows for quick prototyping of Rich Internet Applications with features like grids, charts, forms and slides. The tool is open source and its main components include the Ext JS JavaScript library and Google App Engine for backend services like data storage and querying. Examples demonstrate how to create and manipulate sample application data using Google App Engine's non-relational BigTable database and Python code.