Nostimates
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AI agent

Claude-User

AnthropicHonours robots.txt

Fetches a page because a Claude user's request required it. Blocking prevents Claude users from reading your pages in-session.

User-agent string

Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko); compatible; Claude-User/1.0; +Claude-User@anthropic.com

How to verify it

Anthropic publishes crawler IPs at claude.com/crawling/bots.json.

What blocking costs

Blocking prevents Claude users from reading your pages in-session.

robots.txt rule

# Block Claude-User
User-agent: Claude-User
Disallow: /

# Allow everything else
User-agent: *
Allow: /

Robots.txt is enough

Anthropic documents Claude-User as honouring robots.txt. Verify with your logs after deploying — a spoofed agent will keep coming.

Generate a full robots.txt

Pick which AI crawlers to allow or block across all 42 agents and copy the file out.

Open the generator →

Other Anthropic agents