AI crawler · Meta · Search and training under one name
Meta-ExternalAgent: what it is, its user agent, and how to block it
Meta-ExternalAgent is Meta's search and training crawler. Crawls for uses such as training foundation models and indexing content for Meta products. In our 13 October 2026 study, 288 of 2,332 live top sites with readable robots.txt rules (12.3%) disallow Meta-ExternalAgent. Part of the AI crawler list.
What Meta-ExternalAgent does
Operator: Meta. Job: Search and training under one name. Obeys robots.txt.
“By configuring the robots.txt file on your website, you can specify to the Meta web crawlers how you would prefer them to interact with your site. In order to block these crawlers, add a disallow for the relevant crawler to robots.txt.”
Meta-ExternalAgent user agent
robots.txt token: Meta-ExternalAgent (matched case-insensitively).
meta-externalagent/1.1 (+/documentation/sharing/webmasters/web-crawlers)meta-externalagent/1.1Meta says the string in your logs will be similar to one of these.
robots.txt: allow or block Meta-ExternalAgent
Allow
User-agent: Meta-ExternalAgent
Allow: /Block
User-agent: Meta-ExternalAgent
Disallow: /Affects AI answers and citations. One name covers both search and model training, so a Disallow removes you from Meta's search features as well as its training data.
Once a group names Meta-ExternalAgent, it ignores your User-agent: * rules, so copy any paths you still want blocked into it.
How many top sites block Meta-ExternalAgent
Disallow Meta-ExternalAgent in robots.txt
12.3%
288 of 2,332 sites
In our 13 October 2026 study, 288 of 2,332 live top sites with readable robots.txt rules (12.3%) disallow Meta-ExternalAgent.
Sample: Tranco top 5,000, tested once on 13 October 2026 from one Indian fixed-line connection. The robots.txt share counts live sites (home page 2xx) whose rules we could read, as on the AI visibility hub. Method and CSV in the study.
Check your own site
The AI crawler checker reads your robots.txt the way Meta-ExternalAgent does and tests what your firewall returns. To write the rules, use the AI robots.txt generator.
Check your page: free, about 20 seconds, no sign-in
What it checks
- robots.txt for Meta-ExternalAgent
- Finds the group Meta-ExternalAgent obeys under RFC 9309 and the rule that decides your page.
- What your CDN lets through
- Requests the page as OAI-SearchBot, PerplexityBot and Claude-SearchBot and compares the answers with a browser request.
- Content without JavaScript
- AI crawlers don't run JavaScript. The audit checks how much of the page is in the raw HTML.
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Questions
What is Meta-ExternalAgent?+
Meta-ExternalAgent is Meta's search and training crawler. Crawls for uses such as training foundation models and indexing content for Meta products.
What is Meta-ExternalAgent's user agent?+
Meta documents it as: meta-externalagent/1.1 (+/documentation/sharing/webmasters/web-crawlers). Match on the token Meta-ExternalAgent, since version numbers change.
How do I block Meta-ExternalAgent?+
Add "User-agent: Meta-ExternalAgent" followed by "Disallow: /" to your robots.txt. Obeys robots.txt, per Meta.
Does blocking Meta-ExternalAgent affect AI search citations?+
One name covers both search and model training, so a Disallow removes you from Meta's search features as well as its training data.
How many websites block Meta-ExternalAgent?+
In our 13 October 2026 study, 288 of 2,332 live top sites with readable robots.txt rules (12.3%) disallow Meta-ExternalAgent.