Safe Social Media Bots

facebookexternalhit

Operated by Meta

Quick Facts

User-Agent:
facebookexternalhit
Category:
Social Media Bots
Operator:
Meta
Safety:
Safe
Blocking Impact:
Varies - Evaluate before blocking
SEO Impact Score:
0/10
Official docs:
developers.facebook.com

What is facebookexternalhit?

This is the primary crawler for Facebook. It fetches content to generate previews (title, description, image) when a link is shared on Facebook.

This is the primary crawler for Facebook. It fetches content to generate previews (title, description, image) when a link is shared on Facebook. facebookexternalhit 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 facebookexternalhit 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 facebookexternalhit?

❓ **Impact Unknown** - The SEO consequences of blocking facebookexternalhit 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 facebookexternalhit with robots.txt

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

Block completely (robots.txt)
User-agent: facebookexternalhit Disallow: /
Allow all (robots.txt)
User-agent: facebookexternalhit Allow: /
Block private only (robots.txt)
User-agent: facebookexternalhit Disallow: /private/ Disallow: /api/ Disallow: /admin/ Allow: /
Nginx server block
# Nginx: Hard-block facebookexternalhit if ($http_user_agent ~* "facebookexternalhit") { return 403 "Bot blocked"; }
Apache .htaccess
# Apache: Hard-block facebookexternalhit SetEnvIfNoCase User-Agent "facebookexternalhit" bad_bot Order Allow,Deny Allow from all Deny from env=bad_bot
Meta robots tag
<meta name="robots" content="noindex, nofollow">
X-Robots-Tag header
X-Robots-Tag: noindex, nofollow

Is facebookexternalhit safe to allow?

Yes, facebookexternalhit 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 facebookexternalhit 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 facebookexternalhit requests resolve to meta's domain.

What does facebookexternalhit do?

Understanding facebookexternalhit'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 facebookexternalhit?
The official user-agent string for facebookexternalhit is: facebookexternalhit. 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 facebookexternalhit by performing a reverse-DNS lookup on the source IP - legitimate bots resolve back to their operator's domain.
Is facebookexternalhit safe?
Yes, facebookexternalhit 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 facebookexternalhit 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 facebookexternalhit hurt my SEO?
❓ **Impact Unknown** - The SEO consequences of blocking facebookexternalhit 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 facebookexternalhit in robots.txt?
Add the following lines to your /robots.txt file: 
User-agent: facebookexternalhit
Disallow: /
This instructs facebookexternalhit 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 facebookexternalhit respect robots.txt?
Yes - facebookexternalhit 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 facebookexternalhit is crawling my site?
Search your web server access logs for the string facebookexternalhit (case-insensitive grep: grep -i "facebookexternalhit" /var/log/nginx/access.log). You can also check Google Search Console → Coverage → Crawl Stats for Googlebot variants. For facebookexternalhit specifically, filter by user-agent in your log analysis tool (GoAccess, AWStats, etc.).
What is the crawl frequency of facebookexternalhit?
facebookexternalhit crawls at a moderate rate. If you notice excessive traffic in your logs, you can add a Crawl-delay directive: 
User-agent: facebookexternalhit
Crawl-delay: 10
(10 second delay between requests).
Can I block facebookexternalhit from specific pages only?
Yes. Instead of a global Disallow: / you can restrict facebookexternalhit to specific paths: 
User-agent: facebookexternalhit
Disallow: /private/
Disallow: /staging/
Allow: /
This allows facebookexternalhit 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. facebookexternalhit (facebookexternalhit) 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 facebookexternalhit and ensure your pages include <meta property="og:title">, og:description, and og:image.

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