Spring Framework - The Spring Framework provides a comprehensive programming and configuration model for modern Java-based enterprise applications - on any kind of deployment platform.
JUnit - JUnit is a simple framework to write repeatable tests.
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
Grails - An Open Source, full stack, web application framework for the JVM
jHipster - JHipster is a development platform to quickly generate, develop, & deploy modern web applications & microservice architectures.
Apache Struts - Apache Struts is an open-source web application framework for developing Java EE web applications.