The disclosed architecture allows markup language (e.g., HTML) pages to facilitate the insertion of content (e.g., text) into an application to which an input method is attached. In this way, a plug-in developer can implement any UI look and behavior using a web page language (e.g., HTML), communicate with a backend datasource just as a regular HTML page, and perform this using any suitable technology. Since the web page is stored in a web server and downloaded to client on-the-fly, install is minimal and users can use the latest version automatically. A broker component receives data derived from code authored in the programming language and embedded in a markup language and provides the additional arbitrary data to the application.