What is Claude-User?

How often is Claude-User impersonated?

For the median organisation, 33% of requests claiming to be Claude-User failed verification.

Measured between 3 July 2026 and 28 September 2026 across organisations protected by Centinel. We only publish a share when at least five organisations each saw enough of these requests. Pooled across all of their requests, the share was 27%: a few large organisations carry most of the traffic, so the median organisation is the better guide to what yours will see.

This directory measures requests between 3 July 2026 and 28 September 2026. The fake crawler report covers its own, earlier window (late June to 21 September 2026), so its figures differ from the ones here. Read it for the method.

Have a request that claims to be Claude-User? Check its IP address.

Should you block Claude-User?

Allow it if

you want the assistant to be able to read and cite your pages when someone asks about them.

Block it if

you do not want Claude fetching your pages for its users.

What blocking changes

Anthropic says Claude will not retrieve your content in response to user queries, which may reduce your visibility in user-directed web search.

To block it, add this group to your robots.txt. Anthropic says Claude-User lets site owners control these user-initiated requests through robots.txt.

User-agent: Claude-User
Disallow: /

robots.txt only asks. It does nothing against a client that ignores it or only pretends to be Claude-User. Stopping those takes verification at your edge.