What is Meta-ExternalAds? Meta's advertising crawler
Meta-ExternalAds is the crawler Meta says crawls the web to improve its advertising and other business products and services.
37 of the 1662 major websites we measure block Meta-ExternalAds in robots.txt (2%). 15 of those sites name it directly in their robots.txt; the rest are covered by a wildcard rule.
Key facts
| Fact | Detail |
|---|---|
| Operator | Meta |
| Used for | Meta's advertising and business products |
| Type | Advertising. Checks or classifies pages for an advertising service. It isn't counted in the AI crawler figures. |
| robots.txt token | Meta-ExternalAds |
| Operator's documentation | Read it here |
What blocking Meta-ExternalAds does
Meta says to block it with a Disallow rule for its token, and that robots.txt changes can take up to 24 hours to apply.
How to allow or block Meta-ExternalAds
Add one of these groups to the robots.txt file at the root of your domain. It is a stated preference that well-behaved crawlers read, not an enforcement mechanism.
User-agent: Meta-ExternalAds Disallow: /
User-agent: Meta-ExternalAds Allow: /
Meta-ExternalAds user agent string
Meta's page doesn't list a full string, so look for Meta-ExternalAds in the user agent field of your logs.
How to verify a request is really Meta-ExternalAds
Anyone can put a crawler's name in a user agent string, so the name alone proves nothing. We did not find a published IP list or reverse DNS rule from Meta.
How to whitelist Meta-ExternalAds in a firewall or CDN
robots.txt only states a preference. A firewall, CDN or bot protection service can still refuse the request, and the crawler then gets an error even though robots.txt allows it.
- Check that no group in your robots.txt blocks it, using the rule above.
- Add an allow rule in your firewall or CDN that matches the name in the user agent. Keep the rule narrow, because anyone can copy a name.
- Check your server logs for a 200 response from Meta-ExternalAds afterwards.
On Cloudflare, also check AI Crawler and Agent access policies, which can block search, agent and training traffic across a site.
Why Meta-ExternalAds gets a 403 or 405 error
A 403 means the server refused the request, which usually points to a firewall or bot rule. A 405 means the server refused the request's method, so check any rule that only permits certain methods. A crawler that obeys robots.txt won't request a page it is told to avoid, so an error in your logs points to your server's configuration. To stop it deliberately at the server, this nginx rule returns a 403:
if ($http_user_agent ~* "Meta-ExternalAds") {
return 403;
}Who blocks Meta-ExternalAds, by sector
| Sector | Sites measured | Blocking | Share |
|---|---|---|---|
| Social and media platforms | 115 | 9 | 8% |
| News publishers | 182 | 9 | 5% |
| Reference and research | 114 | 4 | 4% |
| Finance and business media | 94 | 3 | 3% |
| AI companies | 128 | 3 | 2% |
| Technology media | 126 | 3 | 2% |
| Developer references | 159 | 1 | 1% |
| E-commerce and retail | 92 | 1 | 1% |
| Government and institutions | 98 | 1 | 1% |
| Hosting and infrastructure | 98 | 1 | 1% |
| SaaS platforms | 196 | 2 | 1% |
| Health publishers | 88 | 0 | 0% |
| SEO and marketing tools | 86 | 0 | 0% |
| Travel | 86 | 0 | 0% |
Sites blocking Meta-ExternalAds
academia.edu, afterpay.com, barrons.com, consilium.europa.eu, devclass.com, distill.pub, eluniversal.com.mx, facebook.com, flickr.com, fortinet.com, hackernoon.com, imdb.com, instacart.com, instagram.com, linguee.com, lobste.rs, magento.com, marketwatch.com, meta.ai, netflix.com, news.com.au, poe.com, reddit.com, sap.com, sciencedirect.com, sr.ht, theregister.com, thesun.co.uk, thetimes.co.uk, threads.net, todayonline.com, torontosun.com, vancouversun.com, wordreference.com, wsj.com, x.com, yomiuri.co.jp.
Sites that allow Meta-ExternalAds by name
ai.meta.com, disneyplus.com, getyourguide.com, khaleejtimes.com, pinterest.com, reuters.com, slate.com, whatsapp.com, zeit.de.
Other Meta crawlers
Meta-ExternalAgent (model training), Meta-ExternalFetcher (on-demand fetch), Meta-WebIndexer (Meta AI search index), facebookexternalhit (link preview).
See all 36 AI crawlers, the rule change log or the full study. Being reachable is only the first step: how AI search engines choose what to cite covers the rest.
Cite this data
You are welcome to quote or republish these figures. Please credit IndexHalo with a link to this page (CC BY 4.0). All our datasets are on the data page.
IndexHalo. "Meta-ExternalAds block rate across major websites." Measured 12 November 2026. https://www.indexhalo.com/ai-crawlers/meta-externalads/
<a href="https://www.indexhalo.com/ai-crawlers/meta-externalads/">Meta-ExternalAds block rate across major websites, IndexHalo</a>