OpenXava - OpenXava is a Web Java Framework for Rapid Development of Enterprise Applications.
Vaadin Framework - Vaadin is a web application framework for Rich Internet Applications (RIA).
Apache Sling - Apache Sling is a REST based web framework,
Kissflow Low Code - Kissflow offers a Low Code BPM tool that enables you to build workflows and administer tasks without technical knowledge.
Grails - An Open Source, full stack, web application framework for the JVM
Eclipse RAP - Java Web Frameworks