The most prominent example of this in the real world was the (or similar tools like "Marauders Map" in the past). These tools rely on a discrepancy between what users think is private and what is actually public.
In 2015, a developer named Alon Kollmann released a Chrome extension called Facebook Friends Mapper facebook friend mapper chrome extension
Here is the reality check. While the technology is cool, using a operates in a legal gray area. The most prominent example of this in the
: Using such automated tools can lead to your Facebook account being temporarily locked or "checkpointed" by Meta's security systems. Malware & Data Leaks facebook friend mapper chrome extension