Tool
What the Image Alt Tag Checker does
Image Alt Tag Checker: checks Images found and Missing alt attribute from Page HTML.
Point it at Page HTML and it returns Images found and Missing alt attribute. Edit a field and the answer updates in place.
Typical users are site owners checking their markup. Structured data is easy to get subtly wrong and hard to notice when you do.
The markup you paste is analysed locally, so unpublished pages stay unpublished.
The sections that follow cover the fields, the method, and one full example computed from the defaults.
What do the Image Alt Tag Checker fields mean?
The Image Alt Tag Checker uses 1 input. Each input has a default that makes sense on its own, so a partial edit still gives a valid result.
| Field | What to enter | Default |
|---|---|---|
| Page HTML | paste or type any amount of text | <img src="/hero.png" alt="Team reviewing a mortgage document"> <img src="/chart.png"> <img src="/spacer.gif" alt=""> |
How does the Image Alt Tag Checker work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same check.
Values are checked first: an out-of-range or non-numeric entry names the offending field instead of returning nonsense.
What a typical run looks like
You provide: Page HTML
What happens: the file is read into memory by your browser, processed locally, and offered back as a download. It is never uploaded.
You get back: a processed file plus a short status summary in the tool panel.
The tab does the processing, so speed tracks your hardware and very large files fail on memory rather than on a quota.
Alt text serves three audiences, not one
Missing alt text is simultaneously an accessibility failure, a missed image-search opportunity, and a resilience gap, three separate reasons that all point at the same fix.
Worth knowing
- For a screen reader user, a missing alt attribute means the filename gets read aloud instead of a description: "IMG dash 4471 dot jpg" instead of whatever the image actually shows. This is the basis of WCAG success criterion 1.1.1, a genuine access barrier rather than a cosmetic one.
- An empty alt="" is the correct, deliberate way to mark a purely decorative image. It tells assistive technology to skip it entirely rather than announce a redundant "image" with nothing useful to say. Treat empty alt as a pass, not a gap.
- Descriptive alt text is one of the only signals Google Images has about what a picture shows, since it cannot fully interpret an arbitrary photograph the way it parses text. A well-described image is discoverable there in a way an alt-less one is not.
- Alt text also functions as a fallback: if an image fails to load, the alt text is what a sighted user sees in its place instead of a blank box.
How to use it
- Paste your content into Page HTML.
- Each keystroke triggers a fresh calculation, which is cheap because it happens locally.
- You get Images found and Missing alt attribute back.
- Copy Link is the quickest way to send the exact scenario to someone else.
What this tool does not do
- Search engines weigh hundreds of signals. No single on-page check predicts position.
- This checks what is visible in the page you provide; it cannot see server headers or your live rankings.
- Results are informational: check anything consequential against a second source.
Frequently asked questions
You need Page HTML. Nothing starts empty, which means a single edit is enough to get a meaningful answer.
No. Analysis is local, so no copy of your page content is retained anywhere.
Nothing at all. There is no registration, no paywall and no per-use quota.
The check is exact for the method described above. Where a value is rounded for display, the underlying figure keeps full precision.