HTML Checking for Large Sites

Rocket Validator automatically scans your sites for accessibility issues using the W3C Validator, hosted on our own servers and integrated into our web crawler.

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.

The first occurrence of ID “X” was here.

Element IDs in an HTML document must be unique. The HTML validator is indicating the first occurrence of an ID that is repeated. Check the details for that issue to see web pages affected, and the elements within them, to fix that ID repetition.

Related W3C validator issues

When was the last time you validated your whole site?

Keep your sites healthy checking for A11Y/HTML issues on an automated schedule.