facebookexternalhit (Meta): what it is and how to allow or block it
facebookexternalhit is Meta's fetcher that loads a page when its link is shared on Facebook, Instagram or Messenger, to build the preview. Its robots.txt token is facebookexternalhit.
Facts
- Operator
- Meta
- Category
- Social preview fetcher
- robots.txt token
facebookexternalhit
- Honors robots.txt?
- May bypass (integrity checks). Meta says it might bypass robots.txt when performing security or integrity checks. Meta recommends allow-listing the user-agent strings or, more securely, the IP addresses.
- User-agent example
facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)
- Official source
- Meta: Web crawlers
- Compared with the source
What it is used for
Crawls content shared on Meta apps and caches its title, description and thumbnail for link previews. Fetches a page when someone shares its link, to build the preview card (title, description, image). It acts for the person who shared the link.
What happens if you block it
If it cannot fetch the page, shared links lose their preview card.
Your server must support gzip and deflate, and Open Graph tags must appear within the first 1 MB, per Meta.
How to allow or block facebookexternalhit
Add one of these groups to the robots.txt at the root of your domain. A group that names the bot overrides a general User-agent: * group.
User-agent: facebookexternalhit Allow: /
User-agent: facebookexternalhit Disallow: /
Does your site allow facebookexternalhit today? The checker evaluates your robots.txt for this and every other bot.Check my site
What we see on our own sites
No request identifying as facebookexternalhit has been recorded in the last 30 days, so there is nothing to show yet. We never fill this in with estimates.
Counts come from the websites we operate; they hold no IP addresses or URLs, and a user agent is only a claim. See the bot traffic data and the methodology.
Related bots
More from Meta
- meta-externalagent AI training crawlerMeta's crawler that gathers web content to train AI models or to improve products by indexing.
- meta-externalfetcher AI user-triggered fetcherMeta's fetcher that retrieves individual URLs when a user asks, for example to help an AI complete a task.
Other Social preview fetchers
All Social Preview Fetchers · Bot directory · Bots from Meta · Which bots to allow or block · robots.txt generator · See a page as a bot