Grape is a REST-like API framework for Ruby. It's designed to run on Rack or complement existing web application frameworks such as Rails and Sinatra by providing a simple DSL to easily develop RESTful APIs. It has built-in support for common conventions, including multiple formats, subdomain/prefix restriction, content negotiation, versioning and much more. You're reading the documentation for the next release of Grape, which should be 1.1.1. Please read UPGRADING when upgrading from a previous version. The current stable release is 1.1.0.