W3 Validator Services
GoodBotVerifiedBOTA link-checking tool provided by the W3C to verify the integrity and validity of hyperlinks within web documents against open standards. Operated by World Wide Web Consortium (W3C).
What is W3 Validator Services?
W3C-checklink is a specialized diagnostic agent operated by the World Wide Web Consortium (W3C) as part of their suite of free web validation services. It is designed to crawl specific web pages upon user request to identify broken hyperlinks and verify that site navigation adheres to established web standards. Unlike commercial crawlers, it does not index content for search or data mining, but rather serves as a utility for developers to maintain the technical health of their websites.
Identification
W3C-checklinkWhy it crawls your site
The bot crawls websites exclusively when a user manually inputs a URL into the W3C Link Checker service to perform a validation report. It traverses the requested page's links to check for HTTP status codes and connectivity, ensuring that the site's internal and external references are functional. The W3C provides clear documentation on its IP ranges and user-agent strings, allowing site administrators to identify and manage these requests if they wish to restrict or allow access to their server logs.
Block or allow W3 Validator Services
Add a Disallow rule for W3C-checklink in your robots.txt file. You can also block at the server level using your web server configuration or CDN firewall rules to filter requests matching the user-agent string.
# Block W3 Validator Services from crawling your entire site User-agent: W3C-checklink Disallow: / # Allow W3 Validator Services full access User-agent: W3C-checklink Allow: /
Ensure your robots.txt allows W3C-checklink. Verify requests by checking the user-agent string.
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