# facebookexternalhit

Operator: Meta
Purpose: Link previews
Reviewed: 2026-09-14
HTTP identifier: facebookexternalhit
robots.txt token: facebookexternalhit

## What is facebookexternalhit?

Retrieves previews of links shared in Meta apps.

## How to identify it

Look for the facebookexternalhit identifier in a request’s User-Agent. This is a name match, not identity verification. Version strings may change.

## How to check identity

A User-Agent match identifies a claimed client. Check the source IP and any operator-published verification method before granting access.

## Access and robots.txt

Meta documents robots.txt controls, but FacebookExternalHit may bypass them for security or integrity checks.

Optional full-site opt-out; merge with existing rules only if intended. Not a security control.

```text
User-agent: facebookexternalhit
Disallow: /
```

## What it means in your analytics

A preview fetch can precede a visit or happen without one.

## Useful measures

Shared URLs; Image responses; Preview fetch errors.

## What to check next

Check the shared page’s Open Graph title and image using Meta’s Sharing Debugger.

## Sources

- [developers.facebook.com](https://developers.facebook.com/docs/sharing/webmasters/web-crawlers/)

Operator facts are source-backed; interpretation and actions are Apostl guidance.

## Related profiles

- [meta-webindexer](https://apostl.dev/bots/meta-webindexer)
- [meta-externalagent](https://apostl.dev/bots/meta-externalagent)
- [meta-externalfetcher](https://apostl.dev/bots/meta-externalfetcher)

[Start measuring agent traffic](https://apostl.dev/start/agent-analytics)