Open source, fast, non-blocking webserver written in python. In addition, "Tornado comes with built-in support for a lot of the most difficult and tedious aspects of web development, including templates, signed cookies, user authentication, localization, aggressive static file caching, cross-site request forgery protection, and third party authentication like Facebook Connect. You only need to use the features you want, and it is easy to mix and match Tornado with other frameworks."