Updated 2026-10-20

Image alt text for SEO and accessibility

The alt attribute is the text alternative for an image. Screen readers read it aloud, browsers show it when the image fails to load, and search engines use it to understand what the image shows.

• Accessibility: WCAG success criterion 1.1.1 requires a text alternative for non-text content (W3C: Understanding 1.1.1).
• Search: Google uses alt text, together with the page's content, to understand images, and recommends descriptive, concise alt text over keyword lists (Google Search Central: image SEO).

Find images without alt

grep -rhoP --include='*.html' '<img(?![^>]*alt=)[^>]*>' dist

That needs GNU grep for -P (or use rg -P). Browser tools such as Lighthouse's accessibility audit list them too, and the free site checker counts images without alt across up to 50 pages of your live site.

How Headlark writes alt text

• Only images whose alt is missing or empty get one. Alt text you wrote is never changed.
• Each is a short description, up to 125 characters, written in the page's language from the page's context: the surrounding text, headings and the image's file name.
• Headlark doesn't look at the image itself. On a page about a bakery, hero-brod.jpg becomes "Nybakade surdegsbröd från bageriet i Uppsala" because the page says so, not because the pixels were analysed. Check alt text on images whose meaning the page doesn't explain.
• Spacers and tracking pixels are meant to be skipped. Note that an intentionally empty alt="" on a decorative image counts as missing today, so it may get a description.

Where it applies

• Build step: written into the <img> tags in your HTML, for every reader and crawler.
• Snippet: applied in the browser. Screen readers in the browser get it; crawlers other than Google don't.
• Webflow: alt text isn't part of Webflow's page settings API, so it needs the snippet.

Try it

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