ZoomingProxy 
Rack middleware implementing the zooming-proxy spec
Installation
Add this line to your application's Gemfile:
gem 'zooming-proxy'
And then execute:
bundle
Or install it yourself as:
gem install zooming-proxy
Quick Start
# require the proper libraries in your project
require 'zooming-proxy'
# enable the middleware in your `config.ru`
use ZoomingProxy::Middleware
# make a request, to see if things work as expected
curl -sI 'https://example.org/hello/world' | grep 'X-HAL-Zoomed'
# => X-HAL-Zoomed: 1
License
The gem is available as open source under the terms of the MIT License.