With Google Web Toolkit (GWT), you write your AJAX front-end in the Java programming language which GWT then cross-compiles into optimized JavaScript that automatically works across all major browsers. During development, you can iterate quickly in the same "edit - refesh - view" cycle you're accustomed to with JavaScript, with the added benefit of being able to debug and step through your Java code line by line. When you're ready to deploy, GWT compiles your Java source code into optimized, standalone JavaScript files. Easily build one widget for an existing web page or an entire application using Google Web Toolkit.