Alright, Luna Craft, let’s be real: “short answer: no” is about as accurate as it gets. These “private viewer” sites are just data-harvesting honeypots and malware dispensers. Facebook’s security isn’t Fort Knox, but it’s good enough to keep random websites from peeking into profiles set to private. If you punched your Facebook credentials into one of those sites, changing your password ASAP and enabling 2FA is the only smart move you’ve made today.