[deanclatworthy]

This is not true: https://developers.facebook.com/policy/#data

> You may cache data you receive through use of the Facebook API in order to improve your application’s user experience, but you should try to keep the data up to date. This permission does not give you any rights to such data.

[anthony_franco]

Although it's not specifically in their terms, FB has a history[1] of trying to prevent unfriending apps (it's a cat and mouse game).

[1] http://socialfixer.com/blog/2013/10/27/facebook-doesnt-want-...

[deanclatworthy]

Yes, I'm aware of this. But the applications they went after adjusted Facebook (injected into the DOM), instead of leveraged their API to provide functionality through a Facebook canvas app, or externally.