This starts the application in the browser or in the runtime engine and Flash Builder connects to the current application for control and introspection. So then and I know : Flex is the only technology that generates generates for iOS Android Windows and Mac without writing a single OS-specific code. The software automatically scans your computer for the product keys and serial numbers that the software stores in the registry or in the cache. If you want to develop an application larger than those that require some animation you will have some problems in Flash Builder. This is much more difficult than in Flash Professional. Design interactive experiences that are consistently available on desktops and on multiple devices including tablets smart phones and televisions.