Gemfile

config.ru

$:.unshift File.dirname(__FILE__)

require 'bundler/setup'
require 'rubygems'
require 'grape'
require 'twitter/api'

run Twitter::API

Gemfile

source 'https://rubygems.org'

gem 'grape'

twitter_api.rb

# really stored in twitter/api.rb

module Twitter
  class API < ::Grape::API
    version 'v1', :using => :header, :vendor => 'twitter'
    format :json

    desc "Typical endpoint"
    get :endpoint do
      "lol"
    end
  end
end