{
 "category": "preview",
 "label": "Link preview fetchers",
 "description": "Read your Open Graph tags when someone shares a link. Blocking these is almost always an accident.",
 "count": 1,
 "crawlers": [
  {
   "slug": "facebookexternalhit",
   "name": "facebookexternalhit",
   "operator": "Meta",
   "operator_slug": "meta",
   "category": "preview",
   "category_label": "Link preview fetchers",
   "robots_token": "facebookexternalhit",
   "user_agent_substring": "facebookexternalhit",
   "user_agent_example": "facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)",
   "respects_robots_txt": "documented",
   "respects_robots_txt_label": "obeys robots.txt (documented)",
   "verification_method": "none",
   "verification_label": "no published verification method",
   "published_ip_ranges_url": null,
   "ip_ranges_endpoint": null,
   "ipv4_prefix_count": 0,
   "ipv6_prefix_count": 0,
   "what_it_is": "The link unfurler: it reads your Open Graph tags when somebody shares your URL on a Meta property.",
   "cost_of_blocking": "Severe and usually accidental. Your links share as bare grey boxes with no title, image or description across Facebook, Instagram, Messenger and WhatsApp. Almost nobody means to block this.",
   "operator_docs": "https://developers.facebook.com/docs/sharing/webmasters/web-crawlers",
   "html_url": "https://www.pathwren.workers.dev/crawler/facebookexternalhit.html",
   "json_url": "https://www.pathwren.workers.dev/crawler/facebookexternalhit.json",
   "last_reviewed": "2026-09-01"
  }
 ]
}