Claude-Agent

A real browser hosted by Anthropic that completes tasks at a user's direction, for example in Claude Duet. It sends the browser's own user-agent with a Claude-Agent token added. IP ranges are published at claude.com/.well-known/sail, and it's managed separately from ClaudeBot, Claude-User and Claude-SearchBot.

What happens if you block it

Users can't have Claude's hosted browser complete tasks on your site. Anthropic's crawlers aren't affected. Anthropic doesn't say whether it follows robots.txt.

Our take

Allow it if you want users' Claude agents to work on your site. The user-agent can be spoofed, so verify against the published IP list before trusting it.

How to block or allow it

It isn't a crawler: requests come from a real browser with the browser's own user-agent, plus a Claude-Agent token. Match on that token, not the full string, in your CDN or firewall. To block it on Cloudflare, add a custom rule with the expression below and the action Block; on Nginx, the second snippet returns 403.

(http.user_agent contains "Claude-Agent")

if ($http_user_agent ~* "Claude-Agent") { return 403; }

Anyone can send that user-agent. Before you trust or allow it, check the request comes from the IP ranges listed at claude.com/.well-known/sail, which change over time, so update rules from the file rather than hardcoding them.

The operator's own words

Allowing or disallowing this traffic will control whether your users can ask their Claude services that leverage this type of agentic browser use to complete tasks on your website.Anthropic documentation, checked 2026-11-05

Other Anthropic agents