AI Crawler & Robots.txt Simulator

Crawlers evaluate robots.txt based on RFC 9309. First, the crawler finds the most specific User-Agent block that matches its identity (exact match takes precedence over wildcard "*"). Second, it evaluates all Allow and Disallow directives against the requested path. When multiple rules match, the directive with the longest pattern length takes precedence. If an Allow and Disallow rule have the exact same length, the Allow rule takes priority.

Googlebot is Google's primary search crawler responsible for indexing pages for Google Search and Google News. Google-Extended is a distinct user-agent token introduced by Google to control whether your content can be used to train generative AI models (such as Gemini, Vertex AI, and Bard). Disallowing Google-Extended prevents your content from training Google's AI models without harming your regular Google Search organic rankings.

Yes. OpenAI distinguishes between foundation model training and live user queries: "GPTBot" is the crawler used to train OpenAI's generative AI models, while "ChatGPT-User" is the user-agent dispatched when an end-user in ChatGPT explicitly requests web browsing or follows a link. You can block GPTBot while permitting ChatGPT-User to keep your site accessible to ChatGPT users.

The robots exclusion standard (RFC 9309) is an ethical protocol, not an cryptographic access barrier. Major search engines and reputable AI companies (Google, Microsoft, OpenAI, Anthropic, Perplexity, Apple) strictly honor robots.txt directives. However, rogue scrapers, lead harvesters, and malicious bots intentionally ignore it. To block rogue scrapers, pair your robots.txt with Cloudflare WAF Bot Management, user-agent challenge rules, and rate limiting.

Per RFC 9309, if a server returns HTTP 404 (Not Found) or HTTP 410 (Gone) for /robots.txt, all crawlers interpret this as "unrestricted access." Search engines and AI scrapers will proceed to crawl and index all publicly accessible URL paths on the domain without limitation.