Image Alt Text Checker
Checks the alt text, dimension attributes and lazy-loading setting of every image on the page. A screen reader cannot read an image without alt text, and image search cannot match it to anything.
- Sign-in requiredMembership is free
- Open on the Pro plan100 runs a day
- Saved to your historyReachable from your account
What does this tool look at?
Everything that decides whether Google can crawl and index your page: tags, redirects, robots, sitemaps and server responses.
- Images with missing or meaningless alt text flagged
- Warning when width/height is absent (layout shift risk)
- loading="lazy" usage and file format breakdown
What this tool measures
Alt text is an image turned into words. A screen reader speaks it, the browser prints it when the file fails to load, and Google Images uses it as the only text it has to index. An image without alt text is invisible in all three places.
The tool extracts every <img> on the page and checks the alt attribute against three separate faults: the attribute missing entirely, left empty, or filled with nothing — “image1”, “DSC_0042”, “untitled”. It also warns about alt text over 125 characters, because a screen reader reads it in one breath and the listener loses the thread.
A second block looks at performance: do the images carry width and height, do the ones below the fold use loading="lazy", and are the files still JPEG/PNG or already WebP.
How to use it
- 1
Pick an image-heavy page
A product listing, a gallery or a long article gives the most findings. The tool only sees <img> tags present in the HTML.
- 2
Start with the “no alt attribute” line
That red item is the only real fault; the rest are improvements. If the count is above zero, take the full list from the table.
- 3
Fill the empty cells in the table
In the table, “(none)” means the attribute is missing and “(empty)” means it was left blank on purpose. Those are different things.
- 4
Collect the size and format warnings for one pass
Missing width/height and moving to WebP are two halves of the same job; doing them together is faster.
When to use it
- To check whether hundreds of product images on a category page all inherit the same template alt text.
- When preparing for an accessibility audit and you want the quickest win closed first.
- When the page jumps around while loading and you need to find the images with no dimensions.
- When image search sends you no traffic at all and you want to know why.
Reading the result
No alt attribute at all
A real fault. If the image carries meaning, describe it; if it does not, use alt="" so a screen reader skips it.
Alt text like “image1”
The attribute exists but carries nothing. Replace the filename or counter with a sentence about what is in the picture.
Alt text over 125 characters
That explanation belongs in a caption below the image or in the surrounding copy, not in the alt attribute.
width/height undefined
The browser cannot reserve the space in advance, so the page shifts when the image arrives. That is what damages your layout shift score.
Every image is JPEG/PNG
Moving to WebP roughly halves the file size at the same visual quality. It is the fastest performance win available.
Questions about the Image Alt Text Checker
Empty: alt="". That makes a screen reader skip it entirely. Omitting the attribute behaves differently — the reader may fall back to announcing the filename. For decorative icons, dividers and background patterns, empty alt is the right answer.
If the thing is genuinely in the picture, yes, inside a natural sentence. Packing unrelated terms into alt text misleads the people who rely on it and can read as a spam signal to a search engine.
Keep it under 125 characters. That is the length common screen readers handle comfortably in one pass. If you need a longer explanation, write a caption under the image or cover it in the body copy.
They do not, and this tool cannot see them. An image painted with background-image has no alt text and is not indexed in image search. Use <img> for anything that carries meaning and leave only real decoration to CSS.
Use it alongside these
The other tools in the same category. Run them together and you see the whole picture.
The tool found the problem. Now for the fix
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