Soundcloud Sinatra authorization example. Created the anonymous gist by mistake and hence, forked it here. This is an example to explain the auth-flow and probably has bugs.

soundcloud.rb

# Soundcloud, after authorization, redirects to a pre-registered URL
# with the user's  code, access_token embedded in the URL which may 
# be an issue! 

# Alternatively, modify the #authorize_url() method such that the url
# that gets generated has a parameter "response_type" of "code" instead
# of "code_and_token" which is the default. 

require 'sinatra'
require 'soundcloud'


class App < Sinatra::Base
  def client_id
    ENV['CLIENT_ID']
  end

  def client_secret
    ENV['CLIENT_SECRET']
  end

  set :port, 9292
  get '/login' do

    client = Soundcloud.new(:client_id => client_id,
                            :client_secret => client_secret,
                            :redirect_uri => "http://localhost:9292/done")                       

    redirect client.authorize_url()
    # Alternatively, the following can be used to control what you get out of 
    # the response from soundcloud
    
    # auth_url = client.authorize_url()
    # auth_url.gsub!("response_type=code_and_token", "response_type=code") To get only the code
    # auth_url.gsub!("response_type=code_and_token", "response_type="token") to get the access_token of user
    # redirect auth_url
  end

  get '/done' do
  
  # the params hash would contain a "code" that is required to generate the
  # access_token which is required for further requests to access the user's
  # profile etc.
    params
    
  # user_token = client.exchange_token(:code => params[:code])
  # Tokens.save! user_token
  # optionally, redirect to /me or /
  # redirect '/'
  end
  run!
end


# Soundcloud embeds the Access code of the user who has logged in the query params. It can be obtained 
# using params[:code] inside the '/done/ url. This code needs to be sent in all future requests to access 
# the user's functions.