Cloud9 users may need to use a different callback URL

[bentonwong]

Cloud9 users may have to use https://{insert cloud9 url}/users/auth/facebook/callback when registering their redirect uri on facebook

[hcarnes]

The directions suggest adding localhost:3000/auth/facebook/callback into the Valid OAuth redirect URIs field. If you don't add http to the front of that URL, Facebook will automatically add https, which does not work. So, it might be helpful if the readme link showed http://localhost:3000/auth/facebook/callback.