ZK Framework is described as 'The most popular open source ajax Java web framework integrating jQuery, Spring, JPA, Hibernate, JavaEE, Grails, Scala and many more. Check the demo to see how powerful it is' and is an app in the Development category. There are four alternatives to ZK Framework for Linux, Mac and Windows. The best alternative is Jmix, which is both free and Open Source. Other great apps like ZK Framework are Play! (Free, Open Source), Vaadin Framework (Freemium, Open Source) and invesdwin-NoWicket (Free, Open Source).
Play is a web application framework, written in Scala and Java, which follows the model–view–controller (MVC) architectural pattern. The Play framework makes it easier to build web applications with Java & Scala.
A naked objects framework for wicket that enables developers to write less boilerplate wicket code. Without sacrificing the flexibility and control you are used from wicket. Improving productivity by a measurable factor and making wicket more fun.