AI crawler · DuckDuckGo · Fetches when a user asks

DuckAssistBot: what it is, its user agent, and how to block it

DuckAssistBot is DuckDuckGo's fetcher for user requests. Fetches pages in real time for DuckDuckGo's AI-assisted answers, which cite their sources. Not used to train AI models. In our 13 October 2026 study, 185 of 2,332 live top sites with readable robots.txt rules (7.9%) disallow DuckAssistBot. Part of the AI crawler list.

What DuckAssistBot does

Operator: DuckDuckGo. Job: Fetches when a user asks. Obeys robots.txt.

“Once you’ve updated the file to disallow the DuckAssistBot user agent, the change will take effect after 72 hours and DuckAssistBot will stop crawling your site.”

DuckDuckGo's DuckAssistBot documentation Published IP ranges (JSON)

DuckAssistBot user agent

robots.txt token: DuckAssistBot (matched case-insensitively).

DuckAssistBot/1.2; (+http://duckduckgo.com/duckassistbot.html)

robots.txt: allow or block DuckAssistBot

Allow

User-agent: DuckAssistBot
Allow: /

Block

User-agent: DuckAssistBot
Disallow: /

Affects AI answers and citations. Blocking it refuses the fetch DuckDuckGo makes when a user asks its assistant to read your page.

Once a group names DuckAssistBot, it ignores your User-agent: * rules, so copy any paths you still want blocked into it.

How many top sites block DuckAssistBot

Disallow DuckAssistBot in robots.txt

7.9%

185 of 2,332 sites

In our 13 October 2026 study, 185 of 2,332 live top sites with readable robots.txt rules (7.9%) disallow DuckAssistBot.

Sample: Tranco top 5,000, tested once on 13 October 2026 from one Indian fixed-line connection. The robots.txt share counts live sites (home page 2xx) whose rules we could read, as on the AI visibility hub. Method and CSV in the study.

Check your own site

The AI crawler checker reads your robots.txt the way DuckAssistBot does and tests what your firewall returns. To write the rules, use the AI robots.txt generator.

Check your page: free, about 20 seconds, no sign-in

What it checks

robots.txt for DuckAssistBot: Finds the group DuckAssistBot obeys under RFC 9309 and the rule that decides your page.
What your CDN lets through: Requests the page as OAI-SearchBot, PerplexityBot and Claude-SearchBot and compares the answers with a browser request.
Content without JavaScript: AI crawlers don't run JavaScript. The audit checks how much of the page is in the raw HTML.

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Questions

What is DuckAssistBot?+

DuckAssistBot is DuckDuckGo's fetcher for user requests. Fetches pages in real time for DuckDuckGo's AI-assisted answers, which cite their sources. Not used to train AI models.

What is DuckAssistBot's user agent?+

DuckDuckGo documents it as: DuckAssistBot/1.2; (+http://duckduckgo.com/duckassistbot.html). Match on the token DuckAssistBot, since version numbers change.

How do I block DuckAssistBot?+

Add "User-agent: DuckAssistBot" followed by "Disallow: /" to your robots.txt. Obeys robots.txt, per DuckDuckGo.

Does blocking DuckAssistBot affect AI search citations?+

Blocking it refuses the fetch DuckDuckGo makes when a user asks its assistant to read your page.

How many websites block DuckAssistBot?+