facebookexternalhit

Preview Bot

Operated by Meta

Last updated:

Allow

Generates link previews when your URLs are shared socially.

Recommended action: Allow access. Blocking breaks social sharing previews.

Category

Preview Bot

Primary use case

Social media link previews

Trust level

Caution advised

robots.txt

Not respected

facebookexternalhit Traffic (Last 90 Days)

Avg Share3.03%
Peak12.88%Apr 23
Total Visits11k
Active Days31/90

What is facebookexternalhit?

facebookexternalhit fetches link previews when someone shares a URL on Facebook, Messenger, or Instagram. It reads Open Graph meta tags to generate the preview card.

What facebookexternalhit means for your site

Every visit from facebookexternalhit means someone shared your URL on Meta. The bot fetches your page to generate the link preview card (title, image, description) that appears in the conversation or feed. These are valuable visibility signals that traditional analytics miss entirely. High preview bot activity indicates your content is being shared and discussed.

What should you do?

  • Allow facebookexternalhit, blocking breaks link previews
  • Ensure Open Graph meta tags (og:title, og:description, og:image) are set on key pages
  • Monitor share patterns to identify which content resonates
  • Use BotSights to track social shares that Google Analytics misses

See facebookexternalhit on your own site

BotSights tracks every facebookexternalhit visit in real time, including which pages it crawls, how often, and from where.

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How to identify facebookexternalhit

facebookexternalhit uses the user-agent "facebookexternalhit". It does not respect robots.txt, which is normal for preview bots since they need access to generate link cards.

facebookexternalhit

How to block facebookexternalhit

Three robots.txt options below. Pick the one that matches your goal. Each snippet lists every known facebookexternalhit user-agent pattern so the rules apply regardless of which one the bot announces. Note: facebookexternalhit does not respect robots.txt. These snippets are documented for completeness, but you will need server- or firewall-level rules (Cloudflare WAF, NGINX, .htaccess) to actually stop it.

Edit robots.txt with care

A single misplaced line can de-index your entire site. Common mistake: pasting User-agent: * followed by Disallow: / blocks every bot, not just facebookexternalhit, including Googlebot. Always paste the snippet between existing rules (not over them), keep the User-agent line scoped to facebookexternalhit's patterns, and verify with Google's robots.txt tester before deploying. If you are not sure, ask a developer first.

Option 1: Block all access

Tells facebookexternalhit not to crawl any URL on your site. Use this when you want the bot completely off your content.

User-agent: facebookexternalhit
Disallow: /

Option 2: Block specific paths only

Keep public content crawlable but exclude sensitive or non-public sections. Add one Disallow: line per path. Replace the example paths with your own.

User-agent: facebookexternalhit
Disallow: /admin/
Disallow: /private/
Disallow: /checkout/

Option 3: Slow down with a crawl delay

Crawl-delay is a voluntary directive that asks the bot to wait the given number of seconds between requests. Useful when facebookexternalhit is hammering your origin and slowing the site down for real visitors, but you do not want to block it outright. The value is in seconds, so 10 means at most one request every ten seconds. Not all bots honour this directive (Googlebot ignores it; Bingbot, Yandex, and many AI crawlers do respect it).

User-agent: facebookexternalhit
Crawl-delay: 10

Frequently Asked Questions

What is the User-Agent for facebookexternalhit?

facebookexternalhit identifies itself with the User-Agent string "facebookexternalhit". This is the signature you will see in server logs when someone shares one of your URLs.

Does a visit from facebookexternalhit mean my link was shared?

Yes. Each visit represents a share event on Meta — someone either sent your URL in a private chat or posted it publicly. This is real share-volume data that traditional analytics like Google Analytics never see, because the visit happens server-to-server.

Should I block facebookexternalhit?

No. Blocking prevents link preview cards from rendering when your URLs are shared on Meta. Shared links without preview cards look broken and get fewer clicks. Always allow preview bots.

How do I improve how my link preview looks on Meta?

Add Open Graph meta tags to your pages: og:title (max ~60 chars), og:description (max ~155 chars), og:image (recommended 1200×630px PNG/JPEG). For X/Twitter add the twitter:* equivalents. Test with Facebook's Sharing Debugger or LinkedIn Post Inspector.

What image dimensions work best for facebookexternalhit?

1200×630 pixels (1.91:1 ratio) is the safest size that renders well on most platforms. Keep file size under 5MB and use PNG or JPEG. Avoid text near the edges since some platforms crop.

Why does my link preview show the wrong image?

Meta cache previews aggressively. After updating og:image, use the operator's debugger tool (e.g. Facebook Sharing Debugger, LinkedIn Post Inspector, X Cards Validator) to force a re-fetch, or add a query string to bust the cache.

Does facebookexternalhit respect robots.txt?

No. facebookexternalhit does not respect robots.txt — preview bots typically must access the page to render the share card. This is industry standard for preview fetchers.

Official Meta documentation

Detect social shares that analytics tools miss

Every visit from facebookexternalhit means someone shared your link. BotSights tracks these invisible shares so you know which content resonates.

  • See when your links are shared on social platforms
  • Track which pages get shared most
  • Discover social traffic your analytics can't see
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