AI agent · August 2026
Claude-User in robots.txt: who blocks it
0.7% of the 15,009 sites in the census name Claude-User in their robots.txt, and 78.0% of those block it.
Sites naming it
- Sample
- n=15,009
- Coverage
- 100.0%
The August 2026 crawl, parsed for a robots.txt rule naming this user-agent, on the same 0.1% sample of the corpus as every other figure on this site — 15,009 sites. It used to be measured on the whole corpus and this note used to say so; it moved to the monthly sample when the axis gained a series, so it now carries the same margin as everything else.
Sites blocking it
- Sample
- n=15,009
- Coverage
- 100.0%
What Claude-User actually does
Run by Anthropic. Fetches a page because a person asked Claude about it. Blocking it means that when someone asks about your page, the assistant cannot open it.
What to write in your robots.txt
Put the rule in its own group. A Disallow under User-agent: * predates these agents and several of them do not treat it as applying to them — which is also why this census does not count it.
User-agent: Claude-User
Disallow: /User-agent: Claude-User
Allow: /