Download and unzip the GWT SDK. This contains the core libraries, compiler, and development server that you need to write web applications.
On Windows, extract the files from the compressed folder gwt-2.7.0.zip. On Mac or Linux, you can unpack the package with a command like:
The GWT SDK doesn’t have an installer application. All the files you need to run and use the SDK are located in the extracted directory.
Also, you need to have the the Apache ant installed on your system in order to be able to run the web application locally. On mac you can install it using following command.It installs the apache using mac port.
sudo port install apache-ant