What is Claude-User? How to allow or block Anthropic's crawler

Claude-User is Anthropic's agent for AI search and live answers. Fetches pages on behalf of a user during a Claude conversation.

Anthropic documents Claude-User alongside its other agents; it fetches single user-requested pages rather than crawling at scale.

Add "User-agent: Claude-User" followed by "Disallow: /" to your robots.txt file. The change takes effect the next time the bot fetches your robots.txt.

No. Claude-User is separate from Googlebot, which handles Google Search indexing. Blocking Claude-User has no effect on your traditional search rankings, but it does remove your pages from the AI answers Anthropic's assistant serves to its users.

Search your server access logs for the string "Claude-User" — for example: grep -i "Claude-User" /var/log/nginx/access.log | wc -l. Our free AI Bot Log Analyzer does this in your browser: paste a log file and it counts hits per AI crawler, including Claude-User, with per-path breakdowns.

You don't — Claude-User isn't a tool you run. It's Anthropic's own crawler, operated by Anthropic, that visits your site from their infrastructure. The only control you have over it is whether you allow or block it, via robots.txt or a server rule. If you're looking to crawl other sites yourself, you'd write your own crawler or use a crawling library; sending "Claude-User" as your user agent would be impersonating Anthropic.

Almost certainly not. Crawl-delay was never part of the original robots.txt specification — Google has publicly said it ignores the directive, and the AI crawlers that model their parsers on Google's do the same. Anthropic publishes no position on crawl-delay for Claude-User, so treat it as unsupported. If Claude-User is hitting your site harder than you want, rate-limit it at the server or CDN instead: a Cloudflare rate-limiting rule or an nginx limit_req zone matched on the user agent will actually be enforced, whereas a crawl-delay line is only a request that this agent likely never reads.

Anthropic states Claude-User honors robots.txt, so if you are still seeing hits the cause is usually one of four things rather than the bot misbehaving. First, robots.txt is cached — Anthropic may be working from a copy fetched up to 24 hours before your change. Second, the rule may not match: robots.txt user-agent matching is on a prefix of the token, and a typo or a trailing character breaks it silently. Third, the block may sit under a different user-agent group than the one this bot reads, since a bot obeys only the most specific group that matches it, not the wildcard group as well. Fourth, the traffic may be something else sending Claude-User as its user agent, which anything can do.

Treat it as no unless Anthropic says otherwise. Rendering JavaScript costs an order of magnitude more than fetching HTML, and most AI crawlers — unlike Googlebot, which runs a full headless Chrome — read the raw HTML response and stop there. The practical consequence: anything your page loads client-side after the initial response is likely invisible to Claude-User. If your main content is client-rendered, server-render it or pre-render it so the text exists in the first response.

Anthropic publishes no IP-range file for Claude-User, which means there is no way to verify a request really came from them. Any traffic claiming this user agent should be treated as unverified. If you need certainty, block on the user agent and accept that you may be blocking impostors rather than the real crawler — and note that the absence of published ranges is itself a signal about how seriously the operator treats crawler transparency.

There is no fixed schedule. Claude-User serves live answers, so its crawl rate tracks demand — pages that come up in Anthropic conversations get fetched more often, and a site nobody asks about may see it rarely or never. Frequency also rises with how often your pages change and how many links point at them. The only way to know for your own site is to measure it: grep your access log for the user agent, or paste the log into our AI Bot Log Analyzer, which breaks hits down by date and path in your browser.

Anthropic publishes it at https://support.claude.com/en/articles/8896518-does-anthropic-crawl-data-from-the-web-and-how-can-site-owners-block-the-crawler. That page is the authoritative source for the user-agent string and Anthropic's stated crawling policy.