Scalatra is a lightweight framework for building web applications and APIs that adhere to the RESTful principles. It has its roots in Ruby's Sinatra. Scalatra allows developers to work close to the core, the HTTP protocol, thus making it good choice when wanting to get maximum performance out of web applications. "Scalatra in Action" introduces Scalatra and the Sinatra model. It covers the framework in its entirety, starting with concepts such as request routing, input handling, actions, and HTTP responses. It then proceeds to more advanced topics, such as data access, handling heavy load, asynchronicity, securing applications, designing and documenting RESTful APIs, and realtime web programming. Purchase of the print book includes a free eBook in PDF, Kindle, and ePub formats from Manning Publications.