Link Validity Check
W3Dir link validity checker
About this crawler
Link Validity Check is a web crawler identified by the regular-expression pattern Link Validity Check in the User-Agent request header. It is categorised as monitoring. Use the regex above to detect, log, allow, or block Link Validity Check traffic in your web server, CDN edge rules, or robots.txt.
Block-rate · top 25k sites
0.33%
Technical details
- Name
- Link Validity Check
- Pattern
Link Validity Check- Tags
- monitoring
- Reference
- http://www.w3dir.com/
- Added
- 2026/05/09
- Instances
- 1 known sample(s)
Sample User-Agent strings
Link Validity Check From: http://www.w3dir.com/cgi-bin (Using: Hot Links SQL by Mrcgiguy.com)
Block this crawler
robots.txt — disallow Link Validity Check:
User-agent: Link Validity Check
Disallow: /
Apache .htaccess — return 403:
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} Link Validity Check [NC]
RewriteRule .* - [F,L]
Nginx — return 403 inside a server block:
if ($http_user_agent ~* "Link Validity Check") {
return 403;
}
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