Facebook phone-number scrape (April 2021)
A dataset of 533 million Facebook users' phone numbers, names, and locations circulated publicly. Facebook said the data was collected by abusing a contact-importing feature, not by a server breach.
The dataset spread across forums for months; Facebook added some rate limits to contact matching.
The incident became a standard reference point for scraping abuse of contact-matching features.
The mechanism — a contact-matching feature resolving external inputs against accounts — is nearly identical to Chess.com's find-friends method.
