HTML Checking for Large Sites
Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
HTML issues tagged as FBML.
FBML - Facebook Markup Language was used to embed Facebook-specific tags on web sites, was retired in 2011 but this still appears on <html> tags on some sites. You should consider removing this from your site and use alternative ways to do that.
Still checking your large sites one page at a time?
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.