This application is based on the Railscasts #235 Devise and OmniAuth (Revised) and the original Railscasts #235 OmniAuth Part 1 and #236 OmniAuth Part 2. It uses omniauth-linkedin and omniauth-twitter gems but can be configured to add others such as Facebook, Foursquare and others. See a good list with links to the gems at www.omniauth.org .