Meta-ExternalFetcher
Meta-ExternalFetcher is a bot operated by Meta that fetches single pages on demand for an AI assistant. Meta-ExternalFetcher is dispatched by Meta AI products in response to user prompts, when they need to fetch an individual links. It does not honour robots.txt, and a request claiming to be Meta-ExternalFetcher can be checked against the operator's announced ASN.
Also seen as meta-externalfetcher. Rules need to cover every token.
Meta-ExternalFetcher at a glance
| User agent | Meta-ExternalFetcherToken only. The operator has not published a full user-agent string, so match on the substring rather than an exact header. |
|---|---|
| Operator | Meta |
| Purpose | Assistant fetchers |
| Respects robots.txt | Nosource |
| Verification method | Operator ASN check Same AS32934 check as the other Meta agents. This one fetches a single URL a user shared with a Meta AI assistant. https://developers.facebook.com/docs/sharing/webmasters/web-crawlers/ |
| Crawl pattern | Not published |
| Robots.txt tokens | Meta-ExternalFetchermeta-externalfetcher |
| Operator documentation | https://developers.facebook.com/docs/sharing/webmasters/web-crawlers/ |
Meta-ExternalFetcher is dispatched by Meta AI products in response to user prompts, when they need to fetch an individual links.
Allow or block Meta-ExternalFetcher
Paste one of these into the robots.txt file at the root of your domain. Rules are per token, so a block on one crawler leaves every other bot untouched. Meta-ExternalFetcher is documented as ignoring robots.txt, so treat the block below as a statement of intent and enforce it at your CDN.
User-agent: Meta-ExternalFetcher
User-agent: meta-externalfetcher
Disallow: /Blocks every path for this crawler only.
User-agent: Meta-ExternalFetcher
User-agent: meta-externalfetcher
Allow: /Explicit allow. Useful when a wildcard rule above it would otherwise catch this crawler.
User-agent: Meta-ExternalFetcher
User-agent: meta-externalfetcher
Allow: /
Disallow: /account/
Disallow: /checkout/
Disallow: /searchEdit the Disallow paths to match your own account, checkout and search URLs.
What blocking actually costs you
Blocking Meta-ExternalFetcher means a person who asks about one of your URLs gets an error instead of a summary. That is a support and reputation trade-off, not a training one.
Block every crawler in the directory at onceIs that really Meta-ExternalFetcher?
A user-agent header is a string the client chooses. Scrapers copy Meta-ExternalFetcher precisely because site owners allow it. Same AS32934 check as the other Meta agents. This one fetches a single URL a user shared with a Meta AI assistant.
Paste the IP address from your access log below. You will see whether it belongs to a hosting provider, a residential proxy pool or a Tor exit, plus the ASN that announces it, which is what tells you whether the claim holds up.
Other crawlers run by Meta
Related crawlers
Identify crawlers automatically instead of by hand
Agentscan checks a request against published crawler ranges, reverse DNS and hosting data, then returns a verdict your edge can act on. One call per request, no range files to keep up to date.