Grails vs. Kohana vs. webapp2

Grails is a framework used to build web applications with the Groovy programming language. The core framework is very extensible and there are numerous plugins available that provide easy integration of add-on features.

Kohana is an elegant, open source, and object oriented HMVC framework built using PHP5, by a team of volunteers. It aims to be swift, secure, and small.

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.