AI crawler index
What is Claude-User?
Claude-User is Anthropic's fetcher for pages users ask about. Fetches pages when Claude users ask questions that need web content.
At a glance
| Operator | Anthropic |
|---|---|
| Purpose | User-triggered fetch |
| User agent | Not documented by the operator |
| Obeys robots.txt | Yes, according to the operator |
| Published IP ranges | https://claude.com/crawling/bots.json |
| How to verify it | Anthropic says a source IP on its published list indicates the crawler is from Anthropic. |
| Official documentation | https://support.claude.com/en/articles/8896518-does-anthropic-crawl-data-from-the-web-and-how-can-site-owners-block-the-crawler |
Should you block Claude-User?
It visits a page only when a user asks the assistant something that needs it. Blocking it stops the assistant from reading your page in those moments, which costs you citations; and because a person starts each request, robots.txt may not stop it.
Unlike the user agents of OpenAI and Perplexity, Anthropic says Claude-User honors robots.txt. Blocking it may reduce your visibility when users ask Claude to look things up.
How to block or allow Claude-User in robots.txt
Block it everywhere:
User-agent: Claude-User
Disallow: /Allow it everywhere:
User-agent: Claude-User
Allow: /Rules are matched by the token on the User-agent line. Test the result with the robots.txt tester before you publish it.
Other Anthropic crawlers
- ClaudeBot: AI training
- Claude-SearchBot: AI search
Check your own site
The AI crawler checker tells you which AI crawlers your robots.txt lets in, and the log file analyzer shows how often each one actually visits. For the bigger picture, see what AI crawlers are and the full AI crawler index.
FAQ
Claude-User questions
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