'Unfriendly' is an app that keeps track of your friend list for you, when somebody goes missing we'll let you know who was it, just login once then check whenever you like to see who deleted you.
Unlike other apps, 'Unfriendly' is a fully independent and works outside the scope of Facebook API, which means that it will check your entire list, rather then showing only friends that also use the app.
'Unfriendly' is completely safe and secured. Furthermore, your username and password are stored inside your device, and only there!
Sync process is subject to network speed, device performance & etc. On Samsung S4 it took around 2 minutes to sync a friend list of about 300 friends, you can always leave the app (home button) while it syncs and it'll notify when it's done syncing.