We'll create fresh WordPress site with WP-Validate installed. You have 20 minutes to test the plugin after that site we'll be deleted.
WP-Validate indexes your site, collecting all the blog posts, pages and other published content, and submits it to the W3C’s HTML Validator, which then returns the response.
WP-Validate then lists the valid pages, and the invalid pages, with a link to the specific validator URL.