A product page has a heading that says "Wireless Bluetooth Headphones." Right below it is a product image with alt text that says "Wireless Bluetooth Headphones." A sighted user sees the heading and the image and moves on. A screen reader user hears "Wireless Bluetooth Headphones" from the heading, then immediately hears "Wireless Bluetooth Headphones" again from the image. Every product on the page. Every time.
This is one of the most common accessibility failures on the web and one of the easiest to fix once you know where to look.
Why redundant alt text happens
Content management systems auto-populate alt text from the image filename or the nearest heading. Developers add alt text to every image because they know empty alt is bad for accessibility (it is, when the image conveys information). The result is thousands of pages where images have alt text that adds no new information because it just echoes what the surrounding text already says.
WCAG 2.4.4 (Link Purpose in Context) and WCAG 1.1.1 (Non-text Content) both address this indirectly. The core principle is that every piece of accessible content should add information. If removing the alt text would cause no loss of understanding because the heading already communicates the same thing, the image should either have empty alt (alt="") to mark it as decorative, or its alt text should describe something the heading doesn't.
The right fix depends on the image
Decorative images that just illustrate the heading (a stock photo of headphones next to the "Headphones" heading) should have alt="". This tells screen readers to skip the image entirely. The content is fully communicated by the heading.
Informative images that show something the heading doesn't mention need descriptive alt text that complements rather than duplicates. If the heading says "Wireless Headphones" and the image shows them in a specific color with a folding design, the alt should say "Black over-ear headphones folded flat for travel" instead of repeating the heading.
Functional images (buttons, links with images) need alt text that describes the action, not the heading. An image link to a product page should say "View details" or similar, not repeat the product name that's already visible.
What the audit finds
The Redundant Alt Text Audit scans every image on the page and compares its alt text against the text content of adjacent elements: the nearest heading, the nearest caption or figcaption, and any visible text within the same parent container.
It uses normalized string comparison (case-insensitive, whitespace-collapsed) to catch near-duplicates, not just exact matches. "Wireless Bluetooth Headphones" and "wireless bluetooth headphones" are the same text to a screen reader.
The tool also catches partial redundancy. If the heading says "Premium Wireless Headphones" and the alt says "Wireless Headphones," the alt is adding no new information despite not being an exact match.
Each finding shows the image, the redundant alt text, and the adjacent text it duplicates, so you can decide per-image whether to set alt="" or write a better description.
If you're building sites that need to pass WCAG audits, The $20 Dollar Agency ($9.99 on Kindle) includes an accessibility checklist that catches problems like this before they reach production.
Fact-check notes and sources
- WCAG 2.1 Success Criterion 1.1.1 (Non-text Content) requires that non-text content has a text alternative that serves the equivalent purpose. Source: W3C WAI, WCAG 2.1.
- WCAG 2.1 Success Criterion 2.4.4 (Link Purpose in Context) requires that each link's purpose can be determined from the link text together with its context. Source: W3C WAI, WCAG 2.1.
- The W3C WAI Images Tutorial recommends
alt=""for decorative images. Source: W3C WAI, "Images Tutorial: Decorative Images." - Screen readers such as NVDA and JAWS read alt text immediately after the preceding heading in the DOM order, creating the double-announcement experience.
Related reading
- WCAG accessibility audit — the full accessibility picture
- Image alt audit — finding missing alt text across all images
- Image licensing credit audit — proper attribution for images you use
- ADA litigation risk audit — legal exposure from accessibility gaps
This post is informational, not legal or accessibility-consulting advice. Mentions of WCAG, W3C, NVDA, and other third parties are nominative fair use. No affiliation is implied.
