What is facebookexternalhit?
facebookexternalhit is Meta's link preview crawler. It fetches a page when someone shares its link in a Meta app, to build the preview.
- Operator
- Meta
- Purpose
- Builds link previews when content is shared on Meta's apps.
- robots.txt token
facebookexternalhit- Example user agent
facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)- How to verify
- Meta's crawler page gives no IP list and no reverse DNS domain. It says to add the user agent strings or the IP addresses used by the crawler to your allow list, and publishes no list of those addresses.
- Operator documentation
- https://developers.facebook.com/docs/sharing/webmasters/web-crawlers/
- Last verified
How often is facebookexternalhit impersonated?
Other apps also put "facebookexternalhit" in their user agent, so a request carrying the name is not always a claim to be Meta's bot. We show no share.
This directory measures requests between 14 July 2026 and 10 October 2026. The fake crawler report covers its own, earlier window (late June to 21 September 2026), so its figures differ from the ones here. Read it for the method.
Have a request that claims to be facebookexternalhit? Check its IP address.
Should you block facebookexternalhit?
- Allow it if
- people share your pages in Meta's apps.
- Block it if
- you never want previews on Meta's apps. Other link preview clients also use this name.
- What blocking changes
- Links to your pages shared in Meta's apps lose their preview.
To block it, add this group to your robots.txt. Meta says this crawler may bypass robots.txt when it performs security or integrity checks.
User-agent: facebookexternalhit
Disallow: /robots.txt only asks. It does nothing against a client that ignores it or only pretends to be facebookexternalhit. Stopping those takes verification at your edge.
Related bots
- Meta-ExternalAgent (Meta): Crawls for training AI models or improving Meta products.
- Meta-ExternalFetcher (Meta): Fetches individual links on behalf of Meta product users.
- Meta-WebIndexer (Meta): Crawls pages to improve the search results of Meta AI.
- Discordbot (Discord): Visits a link shared in a Discord message to build its preview.
- Pinterestbot (Pinterest): Indexes pages behind Pins and keeps Pin details up to date.
- Slackbot-LinkExpanding (Slack): Fetches a page's meta tags when someone posts its link in Slack.
See which bots reach your site, and which of them are who they claim to be.
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