Spring Framework - The Spring Framework provides a comprehensive programming and configuration model for modern Java-based enterprise applications - on any kind of deployment platform.
OpenXava - OpenXava is a Web Java Framework for Rapid Development of Enterprise Applications.
Grails - An Open Source, full stack, web application framework for the JVM
Vaadin Framework - Vaadin is a web application framework for Rich Internet Applications (RIA).
Spark Mail - Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues
Apache Sling - Apache Sling is a REST based web framework,