It’s called Unfriend Finder, and it works by monitoring your friends list and seeing who has disappeared since you last logged in.
There’s tons of spam on Facebook about finding out who has unfriended you, but this trick actually works.
Unfriend Finder won’t show you who has unfriended you in the past, but it will work for any time you’re unfriended going forwards.
Does that mean Facebook will kill it?
The plug-in doesn’t really do anything fancy besides monitor your friends list and see who has gone missing. Unless Facebook makes changes to its API for developers, Unfriend Finder will probably stick around.
Want to try it? Here’s how to install Unfriend Finder and see who has unfriended you on Facebook.