DuckAssistBot: what it is, what it does with your content, and what blocking it costs
What DuckAssistBot is
DuckAssistBot fetches a page because a person asked for it — they pasted your URL, or followed a link, and asked the assistant to read it. There is no crawl schedule and no training corpus involved. Blocking it means failing a visitor who explicitly asked for your page.
Operator: DuckDuckGo
robots.txt token: DuckAssistBot
User-agent on the wire: not published by the operator
Category: User-triggered fetch
What blocking it actually costs
DuckDuckGo's AI assistant cannot summarise your pages on request.
How to block DuckAssistBot
Add this to your robots.txt:
User-agent: DuckAssistBot
Disallow: /
The token must appear on its own User-agent: line. A named group replaces the User-agent: * group rather than adding to it, so anything you also want disallowed for this crawler has to be repeated inside its group.
How to allow DuckAssistBot
User-agent: DuckAssistBot
Allow: /
An explicit allow is worth writing even when you have no blanket block: it documents the decision, and it survives someone later adding a restrictive User-agent: * rule without thinking about AI crawlers.
robots.txt is not the only thing that can block it
A permissive robots.txt does not mean DuckAssistBot can reach you. WAF rules, Cloudflare's bot-management settings, rate limits and country blocks all sit in front of robots.txt and answer first. A site whose robots.txt welcomes DuckAssistBot and whose edge returns 403 to it is blocked in every way that matters — and nothing in robots.txt will tell you so.
This is the gap the AI Crawler Access Checker was built to close: it reads robots.txt and sends a real request carrying the crawler's user-agent, so you see what the crawler sees.
Official documentation
DuckDuckGo documents DuckAssistBot at https://duckduckgo.com/duckduckgo-help-pages/results/duckassistbot/.
Common questions
- What user-agent does DuckAssistBot send?
DuckDuckGo does not publish an exact user-agent string for DuckAssistBot. Match on the
DuckAssistBottoken in robots.txt rather than on a full string you found elsewhere.- How do I block DuckAssistBot?
Add a group to robots.txt naming the token exactly:
User-agent: DuckAssistBot Disallow: /The group must name
DuckAssistBoton its own line. AUser-agent: *group does not combine with a named one — under RFC 9309 the most specific matching group replaces the wildcard entirely, it does not inherit from it.- What does blocking DuckAssistBot cost me?
DuckDuckGo's AI assistant cannot summarise your pages on request.
- Can I tell a real DuckAssistBot request from a fake one?
Not reliably. DuckDuckGo does not publish verified IP ranges for DuckAssistBot, so the user-agent string is the only signal, and anyone can send it. Treat robots.txt as a statement of policy rather than as enforcement.
Is DuckAssistBot blocked on your site right now?
Reading your own robots.txt only answers half of it — a firewall rule can block DuckAssistBot while robots.txt says it is welcome. The checker tests both.
Check your site free