The W3C XHTML/HTML Validator bookmarklet opens the W3C Markup Validation Service in a new window to validate the page's markup. Passes the current page URL to validator.w3.org with verbose output enabled. Checks for HTML/XHTML syntax errors, missing required attributes, improperly nested elements, and other markup issues. Requires the page to be publicly accessible or same-origin for the validator to fetch content.
Run Validate XHTMLTest run or drag to
bookmarklets bar to install