What is Grape?
You don't need a hand saw to slice an apple. And you don't need to use Rails to write simple APIs. Grape allows you to build lightweight APIs with Ruby when you don't need the heavy lifting power of large frameworks like Rails. It's a REST-like API micro-framework built to complement existing web application frameworks by providing a simple DSL to easily provide APIs. It has built-in support for common conventions such as multiple formats, subdomain/prefix restriction, and versioning.
Who's Using Grape?
With over 2000 watchers and 200 forks on Github, Grape is powering numerous web applications including Elevate, a state of the art POS system from Agilysys, and Artsy.net, a free and open-access platform application funded by leading visionaries in the tech industry that aims to make art accessible to anyone with an Internet connection.
Grape is available as a gem, to install it just install the gem:
gem install grape
If you're using Bundler, add the gem to Gemfile.