DuckAssistBot: Robots.txt & Crawl Policy Reference

AI Summary: DuckAssistBot is an AI assistant crawler operated by DuckDuckGo. It visits websites in real-time to generate instant AI-assisted answers for search queries. It prominently cites sources but does not index the web for general search or train foundational models.

Role and policy boundary

DuckAssistBot is an assistant-driven crawler. It fetches specific web pages when a DuckDuckGo user's query triggers the DuckAssist feature to generate an instant answer. This is fundamentally different from a background indexing crawler or a training bot. When allowed, it helps your content appear as a cited source in DuckDuckGo's AI answers.

A robots rule is a declaration of intent; it does not replace authentication, authorization, or rate limiting. Start with a dedicated group:

User-agent: DuckAssistBot
Allow: /
Disallow: /staging/
Disallow: /internal/

To stop access for the entire site, use:

User-agent: DuckAssistBot
Disallow: /

Avoid assuming that User-agent: * expresses the same business intent. A wildcard can affect assistant and training crawlers too, and it makes later audits harder because the source of the decision is less specific.

Layered verification

Verify the same URL through each control plane instead of assuming that one green signal represents the whole request path. Compare the bot-specific robots group, the page-level metadata, and the response headers captured at the public edge.

To control DuckAssistBot, you should target its specific User-Agent in your robots.txt. Because it operates as an assistant, blocking it means DuckDuckGo will not use your content to generate real-time AI answers, but it does not affect your visibility in standard DuckDuckGo search results (which relies on DuckDuckBot).

The Policy Engine evaluates the selected user-agent, path scope, and the other supplied layers independently. It can therefore explain why a bot is allowed while another is blocked, rather than returning one blended website score.

Page-level directives can still override the intended outcome for indexing:

<meta name="robots" content="noai, noimageai">

X-Robots-Tag: noai, noimageai

If a response uses these tags, the report marks the result as blocked or conflicting even if the crawler-specific robots group is permissive. This is especially important for canonical pages served through an edge cache where headers may differ from the origin response.

WAF and Nginx remediation examples

Since DuckAssistBot is an active crawler, it can be identified and logged at the network edge. A Cloudflare WAF rule can monitor its access:

{
  "description": "Log DuckAssistBot access",
  "expression": "lower(http.user_agent) contains \"duckassistbot\"",
  "action": "log"
}

Use your platform's actual middleware response pattern rather than copying this simplified example without review. Never place a secret, verification token, or internal policy identifier in a public response header.

map $http_user_agent $block_duckassistbot_private {
    default 0;
    ~*duckassistbot 1;
}

server {
    location ~ ^/(admin|account|private|licensed|internal|api)/ {
        if ($block_duckassistbot_private) { return 403; }
        try_files $uri $uri/ =404;
    }
}

Review checklist

Use this checklist after every policy change and after a CDN or WAF migration. Record the request URL, User-Agent, HTTP status, final redirect, and the exact evidence used to reach the decision.

Verify that the dedicated group appears before relying on a wildcard, test a representative public and private path, and compare live response headers with robots.txt. Keep the policy close to the content owner's intent and record whether the site wants discovery, citation, or no access at all.

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