Free Software for JVM
Play Framework
A framework designed to make it easy to build web applications with Java & Scala. The Play Framework is is based on a lightweight, stateless, web-friendly architecture that follows a model-view-controller (MVC) pattern. While providing predictable and minimal resource consumption (CPU, memory, threads) suitable for highly-scalable applications. Play is written in Scala and can be used for all programming languages that can be compiled into JVM bytecode.
Grails
Grails is powerful Groovy-based web application framework for the JVM built on top of Spring Boot.
ClojureScript
ClojureScript is a compiler for Clojure that targets JavaScript. It emits JavaScript code which is compatible with the advanced compilation mode of the Google Closure optimizing compiler. With ClojureScript, you write browser and web-based applications using Clojure and the REPL, allowing you to write the same Lisp syntax that you are used to in the Clojure ecosystem.