Google Web Toolkit (GWT) it's tool to help you write your front end in the Java programming language and GWT compiles your source into highly optimized JavaScript. Writing web apps today is a tedious and error-prone process. You spend 90% of your time working around browser quirks, and JavaScript's lack of modularity makes sharing, testing, and reusing AJAX components difficult and fragile. It doesn't have to be that way.

High performance JavaScript. GWT produces AJAX apps that:
Load faster than hand-written JavaScript apps
Use smaller, more compact, cacheable code
Automatically support IE, Firefox, Mozilla, Safari, and Opera
Use the browser's "back" button correctly

Better development tools. Since you're writing in Java, you can use:
IDEs that you love like Eclipse, IntelliJ, and NetBeans
Full-featured debugging, with variable watches and breakpoints
Unit tests (based on JUnit) both in a debugger and in a browser

Google APIs and reusable UI components. GWT comes equipped with useful libraries:
Built-in UI components serve as cross-browser building blocks for your app
RPC helps with client-server interaction
JavaScript Native Interface (JSNI) simplifies integrating GWT code with existing JavaScript code

Home page: http://code.google.com/webtoolkit/
Download : version 1.4 for Windows
Sized: 18.7Mb