Image alt text checker

Use this image alt text checker to review every image on a page. See which alt texts are missing, empty on purpose, file names, too long or repeated, and how to fix each one.

Free, no account. Ten checks per hour across the link extractor, heading checker and image alt text checker.

We send the address to our API for this check. Results can be cached for five minutes.

Alt text describes an image for people who cannot see it and for search engines. This checker reads every img tag on a page and sorts the alt text into missing, empty on purpose, a file name, longer than 125 characters, repeated on a different image, or fine, with a fix for each one.

How to use this checker

One page, robots.txt first
Our server reads the site’s robots.txt as AiGrowScan, then requests the page with the limits the SEO checker uses: public addresses on standard ports, every redirect checked, at most 1.5 MB of HTML. No JavaScript runs, so anything a script adds after loading is not read.
Which image address
The src, or the data-src style attribute that lazy loading scripts swap in, or the first srcset candidate. Copies inside noscript are skipped, so a lazy loaded image counts once. CSS background images and images added by scripts are not read.
The statuses
Missing: no alt attribute. Empty on purpose: alt="" or a presentation role, which tells screen readers to skip a decorative image. Empty in a link: the image is all the link holds, so the link has no name. File name: a file name, a camera name such as IMG_1234, a placeholder word or the image’s own file name. Long: over 125 characters. Repeated: the same alt as an earlier, different image.
Where 125 comes from
No standard sets a length for alt text. 125 characters is a common editorial limit, used here as a prompt to move long descriptions into the page text or a caption.

Questions about this checker

Every img should have an alt attribute. Images that carry information need a short description. Decorative images such as dividers should have an empty alt="" so screen readers skip them. An image that is the only content of a link needs alt text that says where the link goes.

Long enough to say what the image shows or does in its context, usually a short sentence. No standard sets a limit. Put a longer description in the page text or a caption.

Google says it uses alt text, with computer vision and the page content, to understand what an image shows. Write alt text that describes the image in context. A list of keywords counts as keyword stuffing.

It ends in .jpg or another image extension, starts like a camera file such as IMG_ or DSC, is a placeholder such as “image”, or matches the file name exactly, hyphens included. “Red shoes” for red-shoes.webp passes; “red-shoes” does not.

Only when the HTML already holds the image, as lazy loading setups with data-src usually do. Galleries and sliders that scripts build after loading are not in the HTML, so they are not listed.

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