HTML Checking for Large Sites
Rocket Validator automatically checks your pages on the W3C Validator.
HTML issues tagged as required attribute.
The src attribute for <img> tags is required, to define the source of the image, like in this example:
<img src="photo.jpg" alt="wombat" />
<img> tags used to display images require the attribute src to indicate the source of the image, for example <img src="/img/photo.jpg" />.
The element X requires an attribute Y, but it’s not present. Check that element and add the required attribute, like in <X Y="value" />.
When was the last time you validated your whole site?
Keep your sites healthy checking for A11Y/HTML issues on an automated schedule.