Butterfly is a modular web application framework written in Java but mainly focused on the use of Javascript on both the client-side and the server-side to make it easier to build modern web applications that rely heavily on javascript and ajax/json conduits.

It also aims at simplifying the making of web applications by maximizing webapp modularity and code reuse across different web applications.

It aims to be extremely small, lightweight and simple to use, with a minimal set of dependencies on libraries other than the Servlet API and with the idea that you should be able to reuse stuff while minimizing the amount of cut and paste between your own code across different projects.

You can use Butterfly without writing a single line of Java, but being written in Java, it also has access the entire range of existing Java libraries for you to use and fits right into your existing Java webapp serving infrastructure.

For more information see the User's guide.