Play vs. webapp2 vs. Volt

Play Framework makes it easy to build web applications with Java & Scala. Play is based on a lightweight, stateless, web-friendly architecture. Built on Akka, Play provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications.

webapp2 is a simple. it follows the simplicity of webapp, but improves it in some ways: it adds better URI routing and exception handling, a full featured response object and a more flexible dispatching mechanism.

Volt is a ruby web framework where your ruby code runs on both the server and the client (via opal.) The DOM automatically update as the user interacts with the page. Page state can be stored in the URL, if the user hits a URL directly, the HTML will first be rendered on the server for faster load times and easier indexing by search engines.