Meta-ExternalAds user agent, IP ranges and robots.txt

Meta operates Meta-ExternalAds, a crawler the operator says crawls the web for use cases such as improving advertising and other business-related products and services. It honors robots.txt under the token meta-externalads. Meta documents no IP range file or reverse-DNS suffix for it; the only guidance is a page-wide note to allow-list user agent strings or IP addresses.

The crawler identifies itself as meta-externalads/1.1 (+/documentation/sharing/webmasters/web-crawlers), and Meta also documents the shorter form meta-externalads/1.1. Meta's description of its job is brief: it crawls the web for use cases such as improving advertising and other business-related products and services. The documentation names no specific product and no content type it targets. Neither JavaScript execution nor crawl rate is documented, so what a site sees is a request stream under that user agent with no operator statement about volume.

Meta's stated purpose is advertising and business products, which is why this registry places it in the 'other' category. Blocking it withdraws your pages from whatever advertising and business-related uses Meta has in mind; the operator does not describe a visible effect on your site, so there is no documented downside such as lost previews or lost search placement. Allowing it lets those uses proceed. The control is a robots.txt group whose User-agent line is the crawler name, meta-externalads, following Meta's page-wide robots.txt guidance; the page does not show the rule in a literal robots.txt example and states no exception for this crawler.

Verification is the weak point. Meta's crawler page publishes no IP file and no reverse-DNS suffix for Meta-ExternalAds, and no ASN either. The only related guidance is page-wide and says a site can allow-list the user agent strings or the IP addresses, adding that IP addresses are the more secure choice, without publishing the addresses on the crawler page. A site owner therefore has the user-agent string to go on and no operator-supplied way to prove a given request is Meta's.

Operator note. A second documented user-agent form is "meta-externalads/1.1". No per-crawler robots.txt exception is stated; the page-wide instruction "In order to block these crawlers, add a disallow for the relevant crawler to robots.txt." applies. The robots.txt token is the crawler name per that guidance; the page's only worked robots.txt example uses meta-externalagent. JavaScript execution and crawl rate are undocumented.