Robots.txt Checker -- Validate Syntax and AI Crawler Access

The Robots.txt Checker fetches and parses the robots.txt file of any domain, validates its syntax, and highlights directives that affect AI crawlers such as GPTBot, PerplexityBot, and Google-Extended. Enter your domain in the tool above to get an immediate analysis.

Robots.txt basics and why AI crawlers change the picture

Robots.txt is a plain-text file at the root of your domain that instructs crawlers which paths they may or may not access. For years, webmasters mainly wrote rules for Googlebot and Bingbot. The rise of AI search engines has introduced a new class of bots -- each with its own user-agent -- that must be explicitly allowed or blocked.

Common AI crawler user-agents include: GPTBot (OpenAI/ChatGPT), PerplexityBot (Perplexity), Google-Extended (Google AI training and Gemini features), ClaudeBot (Anthropic), and OAI-SearchBot (OpenAI web search). If your robots.txt uses a blanket Disallow: / for User-agent: *, it blocks all of these unless they are individually re-allowed.

What the tool above checks

• Syntax validity: detects malformed directives, missing blank lines between agent blocks, and unsupported fields.
• AI bot access: for each major AI crawler, the tool reports whether it is allowed, partially allowed, or fully blocked.
• Crawl-delay directives: excessive delays slow AI indexing; the tool flags values above recommended thresholds.
• Sitemap declarations: checks that a Sitemap line is present, pointing to a valid XML sitemap.
• Wildcard patterns: validates the use of * and $ wildcards that some parsers interpret differently.
• Conflicting rules: when a more specific rule contradicts a broader one, the tool explains which directive takes precedence.

How to interpret the results and act

• If GPTBot or PerplexityBot is blocked: decide whether that is intentional. If you want AI search visibility, add an explicit Allow: / under their user-agent block or remove the blanket deny.
• If Google-Extended is blocked: your pages may be excluded from Gemini's knowledge and from features that draw on Google's AI training corpus. Evaluate the trade-off carefully.
• Do not remove all restrictions blindly. Blocking scrapers and content thieves is legitimate. Target your restrictions: block specific bots or paths, not all crawlers.
• After any edit, re-run the tool above to verify the change is applied correctly before it goes live.
• Combine robots.txt with a well-formed llms.txt to give AI crawlers both permission and a navigation map.

Benchmark: one blocked bot, invisible to an entire platform

AI Overviews now appear on approximately 31% of Google queries. A single incorrect Disallow line targeting Google-Extended can remove your pages from Gemini's answer pool entirely. Similarly, blocking GPTBot means ChatGPT's web-browsing feature cannot read your content at crawl time. The cost is asymmetric: fixing a robots.txt rule takes minutes; recovering lost AI visibility takes weeks.

For ongoing monitoring of your brand's presence in AI answers across all major engines, Sorank tracks citations and visibility automatically.