Facebook Crawler

Operator

Meta

Type

Social Media Agent

Official page

developers.facebook.com

Follows robots.txt

Partly, according to Meta.

In Vireo

Excluded, reported under Link previews

What it does

Fetches pages shared on Facebook, Instagram or Messenger to build link previews (title, description, thumbnail).

The primary purpose of FacebookExternalHit is to crawl the content of an app or website that was shared on one of Meta’s family of apps, such as Facebook, Instagram, or Messenger.

Meta

User agent

Requests from Facebook Crawler carry user agents like these:

facebookexternalua

facebookcatalog/1.0

facebookplatform/1.0 (+http://developers.facebook.com)

Device Detector identifies it with this pattern (a case-insensitive regular expression):

facebook(?:catalog|externalhit|externalua|platform|scraper)

Anyone can put any name in a user agent. Where the operator publishes IP ranges, checking the request's address against them is the way to confirm a visit is genuine.

Worth knowing

Open Graph tags have to sit in the first 1 MB of the page or they get cut off.

Any Open Graph properties need to be listed before the first 1 MB of your website or app, or it will be cutoff.

Meta

How Vireo counts Facebook Crawler

Vireo keeps requests from Facebook Crawler out of your pageviews and visitors and counts them on its bot report under Link previews, so you can see how much it left out rather than wonder why your server logs show more traffic.

Checked by running Vireo Analytics' own bot filter over Facebook Crawler's user agents.

Sources

• Meta: crawler documentation (checked October 2026)
• Facebook Crawler information page (developers.facebook.com)
• Matomo Device Detector, bots.yml (LGPL-3.0)