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DOM Forensics 5 min readJun 16, 2026
Part 6 of 10DOM Forensics series

robots.txt Audit for AI Crawlers

The user-agents that matter for AI visibility are different from the ones that matter for traditional SEO. Your robots.txt may be accidentally blocking the crawlers that determine AI recommendation coverage.

robots.txt is the access control document for web crawlers. It tells crawlers which pages they are allowed to access and which are blocked. Most websites have a robots.txt optimized for traditional search engine crawlers (Googlebot, Bingbot). AI crawlers — which use different user-agent strings — may be permitted, disallowed, or unaddressed entirely. The difference has direct impact on AI visibility.

NexisHub maintains a technical AI crawlability checklist for teams that need to review robots.txt, canonical tags, rendered content, structured data, and machine-readable discovery files together.

AI Crawler User-Agent Strings

The major AI systems use their own crawler user-agents: GPTBot (OpenAI), Claude-Web (Anthropic), GoogleOther (Google AI), PerplexityBot, YouBot, and others. A robots.txt that uses a blanket `Disallow: /` for `User-agent: *` will block all of these crawlers unless they are explicitly allowed. Many sites have this configuration and are unaware that they are blocking all AI crawlers.

The Opt-Out Problem

The AI industry largely uses an opt-out model for crawling: crawlers proceed unless disallowed. Some sites have opted out of AI crawling intentionally (for copyright or privacy reasons). Many have blocked AI crawlers accidentally — through overly broad disallow rules written before AI crawlers existed. The SiteNexis robots.txt audit identifies which AI crawler user-agents are permitted, which are blocked, and whether any blocks appear to be unintentional.

A common accidental block pattern: `User-agent: * Disallow: /` followed by explicit allows for Googlebot and Bingbot. This pattern explicitly allows the two listed crawlers and blocks everything else — including all AI crawlers. The intent may have been to only allow the two named crawlers, but the effect is AI crawler exclusion.

AI Crawler Directives for Autonomous Agents

The emerging `/.well-known/ai-plugin.json` and AI-specific robots.txt directives allow sites to provide structured information for autonomous AI agents: what the site does, what APIs are available, and what the agent is allowed to do. The Recommendation Surface Mapping module in SiteNexis checks for these discovery endpoints as part of the Autonomous Agent Discovery probability score.

Tags: robots.txt AI Crawlers crawl access Agent Discovery