W3ValidatorServices is a bot in the SEO crawlers category, operated by World Wide Web Consortium (W3C).
W3C provides various free validation services that help check the conformance of Web sites against open standards.
SEO crawlers map links, keywords and technical issues for SEO tools and backlink databases. They help the tool's customers, often your competitors, rather than you. Rate limit or block the ones you do not use.
W3ValidatorServices identifies itself with this user agent string:
W3C-checklinkAnyone can copy a user agent string. Transfon Security also checks where each request comes from, so a request that claims to be a known crawler but comes from the wrong network is treated as a fake, not as the real crawler.
We have not confirmed whether W3ValidatorServices follows robots.txt. Add a rule, then check your logs to see that it stopped. robots.txt is a plain text file at the root of your domain, such as https://example.com/robots.txt.
User-agent: W3C-checklink Disallow: /
User-agent: W3C-checklink Disallow: /private/ Disallow: /search
User-agent: W3C-checklink Allow: /blog/ Disallow: /
User-agent: W3C-checklink Allow: / User-agent: * Disallow: /
User-agent: W3C-checklink group, W3ValidatorServices ignores your User-agent: * rules, so repeat any that should still apply.W3C-checklink from W3ValidatorServices's user agent; check World Wide Web Consortium (W3C)'s own documentation if it publishes a different robots.txt name.Treat robots.txt as a statement of your policy, and enforce it where requests arrive.
W3ValidatorServices works for an SEO tool's customers, often your competitors. It adds server load without readers, so rate limit or block it unless you use the tool.
Transfon Security for publishersSEO crawlers map landing pages and links for competitor research. Keep W3ValidatorServices's visits out of campaign data.
Transfon Security for advertisersW3ValidatorServices can map your catalogue, prices and site structure for competitors. Block it unless you use the tool yourself.
Transfon Security for e-commerceAllow W3ValidatorServices only if your team uses the tool; otherwise rate limit it on docs and marketing pages.
Transfon Security for SaaS and APIsrobots.txt is a request, not an enforcement. Transfon Security shows W3ValidatorServices by name in the Top Bots report, so you can see how often it visits and which pages it reads. Block or allow it with a User Agent rule, or slow it down with a rate limit decision rule.
Transfon Security
W3ValidatorServices is a bot in the SEO crawlers category, operated by World Wide Web Consortium (W3C). W3C provides various free validation services that help check the conformance of Web sites against open standards.
We have not confirmed whether W3ValidatorServices follows robots.txt. Add a robots.txt rule, then check your logs to see that it stopped, and block it by user agent if it did not.
Add "User-agent: W3C-checklink" followed by "Disallow: /" to the robots.txt file at the root of your site. To enforce it, block requests whose user agent contains "W3C-checklink" at your WAF. In Transfon Security that is one User Agent block rule.
No. robots.txt is voluntary, so W3ValidatorServices may not follow it, and anyone can send W3ValidatorServices's user agent, so a fake W3ValidatorServices ignores your rule. Enforce the rule where requests arrive, at your WAF, and check the source network.
SEO crawlers map links, keywords and technical issues for SEO tools and backlink databases. They help the tool's customers, often your competitors, rather than you. Rate limit or block the ones you do not use.
Transfon Security identifies every bot in this directory in your traffic reports, flags fake search crawlers, and lets you allow, block or rate limit each bot.
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