meta-externalfetcher

Operated by Meta · Fetches when a user asks

If you block it

A disallow may not stop it.

Fetches a single link on a user’s request, to evaluate and improve agentic AI products.

robots.txt: Says robots.txt may not apply“this crawler may bypass robots.txt rules”
robots.txt caching: Meta says changes take up to 24 hours to take effect, because its crawlers use a cached copy.
User agent: Not published as a full string. Meta publishes only the token.Match on the prefix meta-externalfetcher rather than the whole string: operators version these, and an exact match stops working on the next release.
Verification: No published method.