AI crawlers · Social link previews

`facebookexternalhit`

facebookexternalhit is the link-preview fetcher run by Meta: Facebook link preview. Its operator publishes no IP ranges or DNS names for it, so a request carrying this name cannot be verified. Treat the name in a log line as a claim.

User-agent token	`facebookexternalhit`
Operator	Meta
What it does	Facebook link preview
Kind	link-preview fetcher
Can a request be verified?	No — user agent string only
In a CrawlCheck scan	Read from robots.txt; reported, never scored

Allow or block it in robots.txt

User-agent: facebookexternalhit
Disallow: /

User-agent: facebookexternalhit
Allow: /

Add a group that names it: "User-agent: facebookexternalhit" followed by "Disallow: /". A crawler follows only the most specific group that names it, so once a group names facebookexternalhit, rules under "User-agent: *" no longer apply to it; repeat in that group any Disallow lines you still want.

What blocking it changes

No. It renders the preview card when someone shares your URL. Blocking it breaks those previews, not AI answers.

Other agents from Meta

Meta-ExternalFetcher — Meta AI live fetch
meta-externalagent — Meta AI
Facebot — Meta link crawler
meta-webindexer — Meta web index
FacebookBot — Meta legacy

See what facebookexternalhit and every other named agent receive from your own site: run a free scan. The full catalogue is on AI crawlers and as JSON at /ai-crawlers.json.

Questions about facebookexternalhit

QHow do I block facebookexternalhit in robots.txt?

QHow can I tell if a request from facebookexternalhit is real?

Its operator publishes no IP ranges or DNS names for it, so a request carrying this name cannot be verified. Treat the name in a log line as a claim.

QDoes blocking facebookexternalhit affect whether my site appears in AI answers?

No. It renders the preview card when someone shares your URL. Blocking it breaks those previews, not AI answers.

QDoes CrawlCheck test my site as facebookexternalhit?

Not as a request. CrawlCheck reads the rules your robots.txt sets for facebookexternalhit and reports them. Rules for it are reported and never scored, because refusing it is a policy choice.