When someone sets their profile to private, they are telling Facebook's servers: "Do not send my information to anyone who isn't on my friends list." This is a server-side control. No third-party website you visit can force Facebook's own servers to break this rule. These systems are designed to protect your data, and they are incredibly robust.

When a user sets their Facebook account to "Private," the platform implements strict server-side access control lists (ACLs).

This is the only official method. If they accept, you see everything they post to friends. If they deny, respect their boundary.

: Most "private viewer" tools are scams designed to harvest your personal data, login credentials, or spread malware.

You cannot see the target’s private profile, but you can see posts and photos that the target has been tagged in if your mutual friends have less restrictive privacy settings.