gzip.rb

require 'faraday'
require 'zlib'

module FaradayMiddleware
  class Gzip < Faraday::Response::Middleware

    def on_complete(env)
      return unless env[:body].is_a? String
      encoding = env[:response_headers]['content-encoding'].to_s.downcase
      case encoding
      when 'gzip'
        env[:body] = Zlib::GzipReader.new(StringIO.new(env[:body]), encoding: 'ASCII-8BIT').read
        env[:response_headers].delete('content-encoding')
      when 'deflate'
        env[:body] = Zlib::Inflate.inflate(env[:body])
        env[:response_headers].delete('content-encoding')
      end
    end

  end
end

Faraday::Response.register_middleware :gzip => FaradayMiddleware::Gzip