This gem is like the `warden_openid_auth` gem, except that it only provides support for the very last step of the OAuth code flow, i.e. when the resource server / relying party (your Ruby Web app) validates the bearer token. Use this gem if your client-side Web (or mobile) app will be taking care of the rest of the OAuth2 motions, such as redirecting (or opening a popup window) to the authentication server at login time, managing and refreshing tokens, doing all these unspeakable things with iframes, etc.