The most famous example was the by St调度 (StumbleUpon’s later tools) and similar apps like TouchGraph or SocioMapper . However, Facebook’s API restrictions in 2018–2020 (after the Cambridge Analytica scandal) killed most of these tools.
: Once installed, it added a specific "Reveal Friends" option directly onto a target's Facebook profile. Google Groups The "Detailed Story": Rise and Fall The Flaw (Circa 2015): Facebook Friend Mapper Extension Download
The was originally a Google Chrome extension designed to exploit a logical flaw in Facebook’s privacy settings. Its primary "feature" was the ability to reveal a user's hidden friends list, provided you had at least one mutual friend with that person. The most famous example was the by St调度