Alt attributes on all imagesWhat it checks and how to fix it

What it checks

Looks at every <img> on the page and checks that it carries an alt attribute (an empty alt="" counts: it marks a decorative image on purpose). Passes when every image has one, warns when some are missing it and fails when none of them do. Pages without images are skipped.

Why it matters

Screen readers read out the file name of an image without alt text, or skip it, so blind visitors lose whatever the image was there to say. Search engines rely on alt text to understand images, to rank them in image search and as the anchor text of linked images. A missing alt is also a WCAG 1.1.1 failure, the most common one in accessibility complaints.

How to fix it

Give every informative image a short alt text that says what the image shows or does. Mark purely decorative images
with an empty alt so assistive technology skips them.

<img src="/images/team-offsite.jpg" alt="The support team at the 2026 offsite in Lisbon">
<img src="/images/divider.svg" alt="">
<a href="/pricing"><img src="/images/pricing-icon.svg" alt="Pricing"></a>

In Rails:

<%= image_tag "team-offsite.jpg", alt: "The support team at the 2026 offsite in Lisbon" %>
<%= image_tag "divider.svg", alt: "" %>

For images coming from a CMS, make the alt field required in the editor instead of filling it with the file name.