facebookexternalhit
Born as the link-preview fetcher for shares on Facebook and Messenger, and most of its traffic is still that. Meta has also acknowledged using it for other collection, which is why it appears in AI bot lists despite predating the AI era by a decade.
What it feeds
Meta documents the primary purpose of this fetcher as crawling content that was shared on one of its apps, such as Facebook, Instagram or Messenger.[1] Most of what a site sees under this name is a link preview being built the moment a person pastes a URL. It predates the AI era by a decade and lands in AI bot lists because Meta has acknowledged wider use.
How to identify it
The user agent names the token, a version and a Facebook documentation URL.[2] Meta publishes no address list for it, so verification against an official range is not possible.
Blocking and its consequences
Meta documents that the crawler might bypass robots.txt when performing security or integrity checks such as malware scanning,[3] so a disallow is not a guarantee. Blocking it also breaks link previews: shares of the site on Meta apps lose their title, description and image, which usually costs more traffic than the crawl itself.
Verification
Operator documentation: https://developers.facebook.com/docs/sharing/webmasters/web-crawlers
A user agent is a claim, not a proof: any client can send any name. Where an operator publishes IP ranges, a reverse lookup is the only way to tell a real visit from an impersonation.
Seen by Baseline
Requests from this bot across sites tracked by Baseline, last 30 days. Aggregated over - sites, never reported per site.
References (3)
Last updated 2026-09-05. Written and maintained by Baseline Labs.
