In a world full of malicious bots, what can you do to protect your precious web application? One of the basic things that you really should do is add CAPTCHA capabilities to it. If you are not familiar with the (rather bizarre sounding) term, CAPTCHA is a simplistic way to ensure that a user is actually a real person, and not a computer. This can be done by challenging the user and asking from him to provide a response to a “problem”. Because computers are unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human. The most common way is to ask the user to type letters or digits from a distorted image that appears on the screen.

Here's a tutorial on how to add CAPTCHA capabilities to your GWT application. Secure your GWT apps from spam using this straightforward guide. Find out how via the following link:

JavaCodeGeeks: Adding CAPTCHA to your GWT application