DomainLens

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Robots.txt Checker: Test What Crawlers Are Allowed to Fetch

Fetches the robots.txt file for the host you enter, reports whether it exists and whether it blocks every crawler, and reads the page-level robots directives alongside it.

Paste a full URL to check a specific page, or a bare domain to check the home page.

What this robots.txt checker tests

The three are checked together on purpose. Crawl control and index control are separate mechanisms that people routinely mistake for each other, and a directive in one place is frequently contradicted by a directive in another.

  • Whether /robots.txt exists on the host and returns 200 rather than an HTML error page.
  • Whether the wildcard user-agent group blocks the entire site with Disallow: /.
  • The page's meta robots directive, which controls indexing rather than crawling.
  • The X-Robots-Tag response header, which does the same job for any resource type.

Reading the result

A file that returns 500 is worse than one that is absent: Google may pause crawling the whole host until it recovers, whereas a clean 404 is treated as "nothing is blocked".

FindingWhat it meansUsual fix
robots.txt missingNo file, or it does not return 200Add one, if only to declare the sitemap
Blocks all crawlersDisallow: / in the wildcard groupRemove it — staging rules often ship by accident
meta robots noindexThe page asks to be kept out of the indexConfirm whether that is intentional
X-Robots-Tag noindexThe header does the same at server levelCheck the server or CDN config, not the HTML

What a robots.txt file cannot do

robots.txt controls crawl access and nothing else. It cannot remove a page from search, cannot keep anything private, and cannot consolidate duplicates. Blocking a URL actively prevents Google from seeing a noindex tag on it, which is why the two together leave pages stuck in the index. See noindex vs robots.txt for choosing the right control, and robots.txt examples for the syntax.

Does this checker test a specific user agent?
It reads the wildcard group, which is what applies to any crawler without rules of its own. A bot with a dedicated group obeys only that group, so check bot-specific rules by reading the file directly.
Why does it say the file is missing when I can open it?
Most often the URL returns a 200 HTML page rather than plain text, or the file exists on www while the check followed the non-www host. Both count as no usable robots.txt.

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