HTML Checking for Large Sites
Rocket Validator automatically checks your pages on the W3C Validator.
HTML issues tagged as duplicate attribute.
Attributes in HTML elements must be unique. For example, <a id="one" id="two"> is invalid as the attribute id is repeated.
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.