Vaadin Framework - Vaadin is a web application framework for Rich Internet Applications (RIA).
OpenXava - OpenXava is a Web Java Framework for Rapid Development of Enterprise Applications.
jHipster - JHipster is a development platform to quickly generate, develop, & deploy modern web applications & microservice architectures.
Grails - An Open Source, full stack, web application framework for the JVM
Play Framework - An open source web framework which follows the model-view-controller architecture. It is light-weight, web-friendly, and stateless. It provides minimal overhead for highly-scalable applications.
CheerpJ - The complete Java runtime for modern browsers. CheerpJ is the only solution that can run any large-scale, unmodified Java applications, applets, or libraries in the browser. No downloads or plugins are required.