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What is Meta-ExternalFetcher?

Meta-ExternalFetcher is the agent Meta uses to fetch a link a person asked its AI to read.

User-triggered fetchPartly followsNo way to verify
Operator
Meta
Purpose
User-triggered fetch. Fetches a page when a person asks an assistant about it.
robots.txt token
meta-externalfetcher
Sample user agent
meta-externalfetcher/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/web-crawlers)User agents change with versions. Match on the token, not the full string.
Follows robots.txt
Partly. Meta says it may bypass robots.txt rules, because a person asked for the page.
How to verify
Meta doesn't publish a way to verify it.
Sources
Meta documentation
Last reviewed

Allow or block Meta-ExternalFetcher

Block Meta-ExternalFetcher
User-agent: meta-externalfetcher
Disallow: /

Asks Meta-ExternalFetcher not to crawl any page. Well-behaved crawlers stop; it does not stop anyone who ignores robots.txt.

Allow Meta-ExternalFetcher
User-agent: meta-externalfetcher
Allow: /

Lets Meta-ExternalFetcher crawl everything. You only need this if a broader rule would otherwise block it.

Should you block it?

Meta-ExternalFetcher only visits when a person asks Meta's assistant about your page. Blocking it means the assistant can't read the page that person asked about.

Write a full policy with the AI Crawler Policy Generator

Meta-ExternalFetcher can't be verified

Meta doesn't publish IP ranges, DNS names or signatures for Meta-ExternalFetcher. The user agent is the only signal, and anyone can copy it, so treat a request that claims to be Meta-ExternalFetcher as unproven.

Questions about Meta-ExternalFetcher

Is Meta-ExternalFetcher safe to allow?

Meta-ExternalFetcher reads public pages; it does not log in or submit forms. Whether to allow it depends on whether you want Meta's product to use your pages.

How do I know a request is really Meta-ExternalFetcher?

You can't, from the request alone. Meta doesn't publish IP ranges, DNS names or signatures for it, so the user agent is the only signal, and anyone can copy that.

How often does Meta-ExternalFetcher visit?

It depends on your site; Meta doesn't publish a schedule. Referscope shows the real visits.

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