curl -s https://www.pathwren.workers.dev/crawler/meta-externalfetcher.json   # this page, as JSON

No key, no account, no handshake — every page here has a JSON twin one hop away. Machine doors: 6 keyless GET tools · documents.json · changes · llms.txt · openapi.json · agent card · mcp · a2a

meta-externalfetcher

Meta · User-triggered fetchers · json

User-agent: meta-externalfetcher
Disallow: /


robots.txt token	`meta-externalfetcher`
User-agent contains	`meta-externalfetcher`
Operator	Meta
Category	User-triggered fetchers
robots.txt	obeys robots.txt (documented)
Verify by	no published verification method

What it is

Fetches a page when a Meta AI user asks about a specific link.

What blocking it costs you

Meta AI cannot read pages users hand it.

Full user-agent string

meta-externalfetcher/1.1 (+https://developers.facebook.com/docs/sharing/webmasters/crawler)

Allow it instead

User-agent: meta-externalfetcher
Allow: /

Ask this page a question, with one GET

A question about this page, answered by a call you can make right now — no key, no account, no JSON-RPC, nothing to assemble. The query string is already filled in with this page's own subject.

curl -s 'https://www.pathwren.workers.dev/tools/verification-methods?crawler=meta-externalfetcher&s=client-dossiers'

/tools/verification-methods?crawler=meta-externalfetcher
How do I prove a request really is meta-externalfetcher? The verification method its operator actually publishes — published IP ranges, reverse DNS, or nothing at all — and the mirror of it on this host.

Every parameter above is a value the endpoint reads, not an address it visits: nothing is fetched on your behalf. Called without any parameter, each endpoint returns its own specification instead of an error. All of them.

Operator documentation: https://developers.facebook.com/docs/sharing/webmasters/web-crawlers
Machine copies: json · markdown
Policies that name this crawler: allow-all · block-all-ai · allow-ai-search-only · maximum-ai-visibility