Meta-ExternalAgent: User Agent, robots.txt Rules & Safety

Q: What is the official user-agent string for Meta-ExternalAgent?

The official user-agent string for Meta-ExternalAgent is: meta-externalagent. This is the exact string you must use in robots.txt, Nginx, Apache, or Cloudflare firewall rules to target this bot. User-agent matching in robots.txt is case-insensitive, but the string must be spelled correctly. You can verify that a request genuinely comes from Meta-ExternalAgent by performing a reverse-DNS lookup on the source IP - legitimate bots resolve back to their operator's domain.

Q: How do I block Meta-ExternalAgent in robots.txt?

Add the following lines to your /robots.txt file: User-agent: meta-externalagent Disallow: / This instructs Meta-ExternalAgent not to crawl any path on your site. The Disallow: / directive covers the entire domain including subfolders. To only block specific sections, replace / with the path (e.g., Disallow: /blog/). Note: robots.txt is publicly readable - any bot or human can inspect it at yourdomain.com/robots.txt.

Q: How do I verify if Meta-ExternalAgent is crawling my site?

Search your web server access logs for the string meta-externalagent (case-insensitive grep: grep -i "meta-externalagent" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For Meta-ExternalAgent specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).

Quick Facts

User-Agent:: meta-externalagent
Category:: AI & LLM Bots
Operator:: Meta
Safety:: Safe
Blocking Impact:: Varies - Evaluate before blocking
SEO Impact Score:: 0/10
Official docs:: developers.facebook.com

What is Meta-ExternalAgent?

A generic user-agent used by Meta for external fetching tasks.

A generic user-agent used by Meta for external fetching tasks. Meta-ExternalAgent is operated by Meta to generate rich link previews when URLs are shared on their platform. It sends GET requests to your URL, reads <meta property="og:..."> and <meta name="twitter:..."> tags, and caches the result. Blocking meta-externalagent means all links to your domain shared on Meta appear as raw text without thumbnail, title, or description. This can reduce CTR from social referrals but has zero SEO impact.

What happens if you block Meta-ExternalAgent?

❓ **Impact Unknown** - The SEO consequences of blocking Meta-ExternalAgent are not fully documented. Before blocking, check your analytics to confirm whether this bot generates referral traffic, review your server logs for crawl frequency, and test in a staging environment if possible.

Generally safe to allow; provides legitimate crawling value.

How to block Meta-ExternalAgent with robots.txt

<code>User-agent: meta-externalagent</code> - Matching is case-insensitive. Robots.txt is fetched from the root of each subdomain separately.

Block completely (robots.txt)

User-agent: meta-externalagent
Disallow: /

Allow all (robots.txt)

User-agent: meta-externalagent
Allow: /

Block private only (robots.txt)

User-agent: meta-externalagent
Disallow: /private/
Disallow: /api/
Disallow: /admin/
Allow: /

Nginx server block

# Nginx: Hard-block Meta-ExternalAgent
if ($http_user_agent ~* "meta\-externalagent") {
    return 403 "Bot blocked";
}

Apache .htaccess

# Apache: Hard-block Meta-ExternalAgent
SetEnvIfNoCase User-Agent "meta\-externalagent" bad_bot
Order Allow,Deny
Allow from all
Deny from env=bad_bot

Meta robots tag

X-Robots-Tag header

X-Robots-Tag: noindex, nofollow

Is Meta-ExternalAgent safe to allow?

Yes, Meta-ExternalAgent is a **safe and legitimate** crawler. It is operated by Meta, which publicly documents its crawler at an official URL and follows the Robots Exclusion Protocol (RFC 9309). The user-agent string meta-externalagent is verifiable via reverse-DNS lookup on the crawling IP addresses. You can safely allow it unless you have a specific reason to block (e.g., AI training opt-out or SEO tool visibility).

Verify by reverse-DNS lookup: legitimate Meta-ExternalAgent requests resolve to meta's domain.

What does Meta-ExternalAgent do?

Understanding Meta-ExternalAgent's purpose helps you decide whether to allow or block it.

Generates link previews for social media shares
Fetches Open Graph and Twitter Card metadata
Creates rich snippets when links are posted
Validates and displays website thumbnails
Improves user experience on social platforms

Frequently Asked Questions

What is the official user-agent string for Meta-ExternalAgent?

The official user-agent string for Meta-ExternalAgent is: meta-externalagent. This is the exact string you must use in robots.txt, Nginx, Apache, or Cloudflare firewall rules to target this bot. User-agent matching in robots.txt is case-insensitive, but the string must be spelled correctly. You can verify that a request genuinely comes from Meta-ExternalAgent by performing a reverse-DNS lookup on the source IP - legitimate bots resolve back to their operator's domain.

Is Meta-ExternalAgent safe?

Yes, Meta-ExternalAgent is a **safe and legitimate** crawler. It is operated by Meta, which publicly documents its crawler at an official URL and follows the Robots Exclusion Protocol (RFC 9309). The user-agent string meta-externalagent is verifiable via reverse-DNS lookup on the crawling IP addresses. You can safely allow it unless you have a specific reason to block (e.g., AI training opt-out or SEO tool visibility).

Will blocking Meta-ExternalAgent hurt my SEO?

❓ **Impact Unknown** - The SEO consequences of blocking Meta-ExternalAgent are not fully documented. Before blocking, check your analytics to confirm whether this bot generates referral traffic, review your server logs for crawl frequency, and test in a staging environment if possible.

How do I block Meta-ExternalAgent in robots.txt?

Add the following lines to your /robots.txt file:

User-agent: meta-externalagent
Disallow: /

This instructs Meta-ExternalAgent not to crawl any path on your site. The Disallow: / directive covers the entire domain including subfolders. To only block specific sections, replace / with the path (e.g., Disallow: /blog/). Note: robots.txt is publicly readable - any bot or human can inspect it at yourdomain.com/robots.txt.

Does Meta-ExternalAgent respect robots.txt?

Yes - Meta-ExternalAgent is a well-behaved bot operated by Meta. It fetches and parses /robots.txt before crawling any page, following RFC 9309.

How do I verify if Meta-ExternalAgent is crawling my site?

Search your web server access logs for the string meta-externalagent (case-insensitive grep: grep -i "meta-externalagent" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For Meta-ExternalAgent specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).

What is the crawl frequency of Meta-ExternalAgent?

Meta-ExternalAgent crawls at a moderate rate. If you notice excessive traffic in your logs, you can add a Crawl-delay directive:

User-agent: meta-externalagent
Crawl-delay: 10

(10 second delay between requests).

Can I block Meta-ExternalAgent from specific pages only?

Yes. Instead of a global Disallow: / you can restrict Meta-ExternalAgent to specific paths:

User-agent: meta-externalagent
Disallow: /private/
Disallow: /staging/
Allow: /

This allows Meta-ExternalAgent everywhere except the listed paths. Path matching in robots.txt uses prefix matching - Disallow: /private/ blocks /private/page.html but NOT /public/private/.

Why is my link preview broken when shared on Meta's platform?

If links to your site appear without a preview image or title on Meta, it's likely because: 1. Meta-ExternalAgent (meta-externalagent) is blocked in your robots.txt. 2. Your Open Graph meta tags are missing or malformed. 3. Meta's cache is stale - request a refresh using Meta's debugger tool. Fix: Remove any block rule for meta-externalagent and ensure your pages include <meta property="og:title">, og:description, and og:image.