You cannot view the contents of a safety deposit box that isn't yours by using a "viewer tool." The bank (Facebook) simply refuses to show you. No amount of third-party software can force the bank's servers to hand over data they are programmed to withhold.

: You can see how your own profile appears to the public or specific people by using the "View As" tool in your profile settings. Profile Locking

There are a few grey-area methods that desperate users try. Let's examine them.