Meta-ExternalFetcher: user agent, IP verification and robots.txt
Meta-ExternalFetcher is operated by Meta. It is classified here as Not a crawler (User-triggered fetch). Verification method: None available.
Exact user-agent string
meta-externalfetcher/1.1 (+/documentation/sharing/webmasters/web-crawlers)
robots.txt token: Meta-ExternalFetcher. The user-agent string is self-asserted and can be
forged by anyone. It is a claim, not proof.
How to verify Meta-ExternalFetcher is genuine
Meta publishes no IP range file and no reverse DNS method for Meta-ExternalFetcher. There is no way for anyone, including us, to prove a request claiming this identity is genuine.
How to block or allow Meta-ExternalFetcher
User-agent: Meta-ExternalFetcher
Disallow: /Replace Disallow with Allow to permit it explicitly.
What blocking Meta-ExternalFetcher costs you
This fetcher supports agentic AI navigating websites to complete tasks for users. Blocking it means Meta's assistant cannot act on your site on a user's behalf, which matters more for transactional pages than for editorial ones.
What is specific to Meta-ExternalFetcher
Meta states directly that Meta-ExternalFetcher may bypass robots.txt rules, because it fetches individual links at a user's request. Combined with the absence of any published IP list, this leaves site owners with no enforceable control and no verification path at all: robots.txt may be ignored, and there is nothing to check a source IP against. Of every agent in this reference, this is the one where a claimed identity is least provable. Meta's crawler documentation was last updated on 21 May 2026 and now also lists Meta-WebIndexer, a separate token for Meta AI search quality that did not exist in earlier versions of the page.
Verify a request claiming to be Meta-ExternalFetcher
Check a Meta-ExternalFetcher request against Meta's published ranges
Source
Primary documentation: https://developers.facebook.com/docs/sharing/webmasters/web-crawlers/. Last verified 2026-08-02.
Other Meta crawlers
- Meta-ExternalAgent - AI training and indexing crawler
- Meta-WebIndexer - Meta AI search index
- Meta-ExternalAds - Advertising and business products
- FacebookExternalHit - Link preview fetch