gwt-validator is a small and lightweight framework for validating user input directly on the client side of your Google Web Toolkit driven application.

As being part of your client application, it will be compiled by GWTs Java Script compiler and published with your app.

• It's lightweight: validation takes place on the client
  
• It's independent: no dependencies to other 3rd party libraries
• It's easy to use: no xml configuration hell
• It's Java: the gwt-validator consists of a small bunch of Java classes and nothing else
• It's open source: see how it works and be independent of any vendor