FacebookExternalHit
recommended: allowThe 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. The link might have been shared by copying and pasting or by using the Facebook social plugin. This crawler gathers, caches, and displays information about the app or website such as its title, description, and thumbnail image.
What it does
Fetchers retrieve metadata from web pages to generate link previews in social media platforms, messaging apps, and content aggregators. They're triggered on-demand when users share or post links, fetching information like titles, descriptions, and thumbnail images. Traffic is unpredictable and correlates with how often your content is shared. Viral content may trigger thousands of fetcher requests in a short period. Fetchers typically access only the shared URL rather than crawling your site.
How to identify it
User-agent contains any of:
facebookexternalhitfacebook[FBANFacebookMozilla
Example user-agent string:
facebookexternalhit/1.0 (+http://www.facebook.com/externalhit_uatext.php)
⚠️ Impostors often copy this name. A genuine FacebookExternalHit never matches:
Twitterbot,
Facebot
robots.txt
Well-behaved crawlers honor robots.txt. To control FacebookExternalHit:
Allow full access
User-agent: facebook
Allow: /Block entirely
User-agent: facebook
Disallow: /
Grey-area scrapers ignore robots.txt. Botscope enforces your policy at the edge or origin regardless —
see how →
FAQ
Should I Block facebook?
No. Blocking fetchers prevents link previews from appearing when your content is shared on social media, messaging apps, and other platforms. This significantly reduces click-through rates and social engagement. Link previews are crucial for content distribution.
How Do I Block facebook?
If you want to, you can block or limit facebook's access by configuring user agent token rules in your robots.txt file. The best way to do this is using Automatic Robots.txt, which update automatically as new agents are discovered. While the vast majority of agents operated by reputable companies honor these robots.txt directives, bad actors may choose to ignore them entirely. In that case, you'll need to implement alternative blocking methods such as firewall rules or server-level restrictions. You can verify whether facebook is respecting your rules by setting up Agent Analytics to monitor its visits to your website.
Will Blocking facebook Hurt My SEO?
Blocking fetchers will hurt your social SEO and content distribution. Link previews significantly improve click-through rates from social media, messaging apps, and other platforms. Without previews, your content appears less engaging when shared, reducing social signals that can indirectly benefit search rankings.
Does facebook Access Private Content?
Fetchers only access the specific URLs that users share or embed, without credentials or authentication. They're designed to retrieve publicly accessible metadata and preview information. Fetchers don't crawl beyond the shared URL and can't access private content unless the shared link itself provides public access to otherwise private information.
How Can I Tell if facebook Is Visiting My Website?
Setting up Agent Analytics will give you realtime visibility into facebook visiting your website, along with hundreds of other AI agents, crawlers, and scrapers. This will also let you measure human traffic to your website coming from AI search and chat LLM platforms like ChatGPT, Perplexity, and Gemini.
Why Is facebook Visiting My Website?
facebook visited your site because someone shared one of your URLs on a social platform, messaging app, or another service that generates link previews. The fetcher was triggered when the link was posted to retrieve your page's title, description, and preview image.
How Can I Authenticate Visits From facebook?
Agent Analytics authenticates agent visits from many agents, letting you know whether each one was actually from that agent, or spoofed by a bad actor. This helps you identify suspicious traffic patterns and make informed decisions about blocking or allowing specific user agents.
References
See FacebookExternalHit on your own site
Botscope shows every bot and AI agent hitting your site — and lets you allow, challenge, or block each one. Observe first, enforce when you're ready.
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