robots.txt rules
Copy the group you need into the robots.txt file at the root of your site. Keep only one option per bot.
At a glance
| Detail | meta-externalfetcher |
|---|---|
| Operator | Meta |
| Type | User triggered fetcher |
| What it does | Fetches individual links when a Meta AI user asks for them. |
| robots.txt token | meta-externalfetcher |
| Example user agent | Contains "meta-externalfetcher" |
| Follows robots.txt | Meta says it may bypass robots.txt because it performs fetches requested by a user. |
| How to verify | Match the user agent and check behaviour in your logs. |
| If you block it | robots.txt alone may not stop it. Blocking it at the firewall stops Meta AI reading your page for users. |
| Source | Meta for Developers crawler documentation |
User agent version numbers change over time. Match on the token, not the full string.
What meta-externalfetcher does
Meta-ExternalFetcher visits a page when someone using Meta AI shares a link or asks something that needs the page. It is not a broad automatic crawler.
Should you allow or block it?
Allow it if you want Meta AI to read your pages for people who ask.
If you block it: robots.txt alone may not stop it. Blocking it at the firewall stops Meta AI reading your page for users.
- Training crawlers decide whether your content helps build future models. Blocking them does not remove you from AI search today.
- Search crawlers decide whether AI engines can find and cite your pages. Blocking them usually costs visibility.
- User triggered fetchers read a page because a person asked. Blocking them stops the AI reading you at the moment someone is interested.
How to find meta-externalfetcher in your logs
Search your server or CDN access logs for the token meta-externalfetcher. This command counts visits by IP, path and status code in a standard access log:
grep -i "meta-externalfetcher" access.log | awk '{print $1, $7, $9}' | sort | uniq -c | sort -rn | head
A run of 403 or 503 status codes means your firewall or bot protection is blocking it, even if robots.txt allows it. That is one of the most common hidden reasons sites lose AI visibility.
How to tell if a visit is genuine
Anyone can put meta-externalfetcher in a user agent string, so the name alone proves nothing. Match the user agent and check behaviour in your logs.
Other Meta bots
- meta-externalagent: training crawler. Crawls pages for training Meta's AI models and for indexing content directly in Meta products.