Disallow Rule Impact Simulator
Test your robots.txt Disallow and Allow patterns against a list of URLs before deploying them. See exactly which pages would be blocked and which would remain accessible to search engine crawlers.
Simulate Disallow Rules
Why Test Robots.txt Rules Before Deployment?
A single misconfigured Disallow rule in robots.txt can block critical pages from Google and other search engines, causing them to drop out of search results within days. Unlike most SEO mistakes, robots.txt errors take effect immediately once the file is updated and crawled.
This simulator lets you do a "dry run" of your proposed robots.txt changes. Paste your new rules on the left, your site URLs on the right, and see exactly which pages would be affected before touching your live robots.txt file.
How Robots.txt Pattern Matching Works
Search engines match Disallow and Allow patterns against the path portion of URLs. The matching follows specific rules:
- Path prefix matching:
Disallow: /admin/blocks any URL whose path starts with/admin/, such as/admin/dashboardand/admin/settings. - Wildcard (*): The asterisk matches any sequence of characters. For example,
Disallow: /archive/*/pageblocks/archive/2024/pageand/archive/old/page. - End anchor ($): The dollar sign anchors the pattern to the end of the URL.
Disallow: /*.pdf$blocks/docs/report.pdfbut not/pdf-resources/. - Specificity precedence: When both Allow and Disallow match, the longer (more specific) pattern wins. Equal length or longer Allow patterns override Disallow.
How This Tool Works
- Paste your proposed robots.txt rules (User-agent, Disallow, Allow directives)
- Provide URLs to test against: paste them directly or enter a sitemap URL to extract up to 2,000 URLs
- The simulator parses rules for each User-agent group
- Each URL path is tested against all matching rules, respecting wildcard patterns and Allow/Disallow precedence
- Results show blocked vs. allowed URLs with the specific rule that matched, so you can identify unintended blocks
Frequently Asked Questions
Why should I test robots.txt rules before deploying them?
Deploying untested robots.txt rules can accidentally block important pages from search engine crawlers, leading to deindexing and traffic loss. A simulation lets you preview the impact of Disallow and Allow patterns against your actual URLs before making any changes live.
How do wildcards work in robots.txt Disallow rules?
The asterisk (*) matches any sequence of characters in a URL path. For example, Disallow: /archive/* blocks all URLs under /archive/. The dollar sign ($) anchors to the end of the URL, so Disallow: /*.pdf$ blocks URLs ending in .pdf but not /pdf-guide/ or /pdf-resources/.
What happens when Allow and Disallow rules conflict?
When both Allow and Disallow rules match the same URL, the more specific (longer) pattern wins. For example, if you have Disallow: /private/ and Allow: /private/public/, the Allow rule takes precedence for URLs under /private/public/ because it is more specific.
Does this tool check rules for all user agents?
Yes. The simulator parses all User-agent directives in your rules and tests URLs against each group. Specific user-agent rules are checked before the wildcard (*) catch-all. This mirrors how real search engine crawlers evaluate robots.txt.
How many URLs can I test at once?
You can test up to 2,000 URLs at once. Paste them directly (one per line) or provide a sitemap URL to automatically extract URLs. Sitemap indexes are supported and child sitemaps will be followed to gather URLs.
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