What is FacebookExternalHit?
When someone shares a URL through Facebook, Instagram, Messenger, or a Facebook social plugin, Meta may send FacebookExternalHit to the page. The fetch supplies the information displayed with that shared link. It is prompted by sharing activity rather than by a general crawl of the domain.
Meta gathers and caches the page title, description, and thumbnail image. A common request identity is facebookexternalhit/1.1, sometimes followed by Meta's crawler-information URL. Since preview data is cached, the first share or a refresh may produce a request while later shares can reuse an existing result.
Meta accepts robots.txt preferences for this crawler, but the behavior has an explicit exception. FacebookExternalHit may ignore those rules while performing security or integrity checks, such as looking for malware. Meta can also cache robots.txt for up to 24 hours, so a new rule may not be used immediately.
The crawler's documented work is link-preview collection and safety checking. Meta does not identify FacebookExternalHit as an AI answer fetcher or model-training bot. Traffic from other Meta user agents must be evaluated separately rather than assigning their purpose to this one.
