Image alt text checker
Alt is what image search and a screen reader get. The usual bug is the attribute not being there at all. An empty alt on a decorative mark is correct — this checker does not lump the two together.
What we measure
Every <img> in the HTML we already downloaded. We split the set into: has text, alt="" (decorative), and no alt attribute. Only the last group raises a warning.
We do not fetch the image bytes and we do not invent alt from the filename. A data: URI still counts as an image if it is in an <img> tag.
How to write alt
Describe the picture in a short clause. If the image is a link, the alt is the link purpose, not “logo”. If it is purely decorative, alt="" — do not omit the attribute.
Background images in CSS are not in this count. If the meaning lives only in a background, put it in the document as text or a real <img>.
See the full audit in your workspace