The anchor you can't see: image links and their alt text

The anchor you can't see: image links and their alt text

A frequent omission in anchor audits: image links. When a link wraps an <img>, there is no anchor text — the alt attribute functions as the anchor signal. Auditors who only scrape visible text anchors miss this surface entirely, and badge networks often ship optimized alt text inside image links ("alt='best casino bonus 2024'").

On one hand, image-link alt text is documented by Google as the relevant descriptor for the link. On the other, most commercial link tools report image links as "empty anchor," so a heavily optimized alt-text profile reads as a clean, anchor-less one.

The result is a category of exact-match concentration that hides in plain sight, especially in widget, badge, and infographic campaigns.

The fix:
— Extend anchor extraction to capture alt on image links and fold it into your distribution
— Audit badge and infographic embeds specifically; their alt text is often templated and identical across hundreds of hosts
— Treat empty-anchor image links and alt-text-bearing ones as distinct categories

Limitation: many crawlers don't expose alt for image links, so this data is often unavailable without first-party crawling.

Open question: is image-link alt text weighted equivalently to visible anchor text in over-optimization assessment, or discounted as a lower-confidence anchor source?