Free Online Image Alt Text Checklist
Check supplied HTML for missing, empty, or weak image alt text.
Images are parsed locally in your browser. Broken markup is repaired by the browser parser before the check, so a missing closing tag will not stop the analysis.
Checklist
Image details
| # | Source | Alt text | Status |
|---|
About the Image Alt Text Checklist
Alternative text is the description a screen reader announces when it reaches an image, and it is also the text shown when an image fails to load. Good alt text communicates the purpose of the image in context rather than describing every pixel. This checker accepts a block of HTML, finds every image element, and reviews the alt attribute against a set of practical rules. It reports missing attributes, empty values, overly long descriptions, file-name placeholders, and images marked as decorative.
What makes alt text useful
For a functional image, such as a linked logo or an icon button, describe the destination or action: "Open the account settings" is more useful than "gear icon". For an informative image, state the takeaway the reader needs, not the visual composition. For a decorative flourish, use an empty alt attribute so assistive technology skips it. Charts and infographics usually need a short alt plus a longer description nearby, because a single sentence cannot carry the full data story.
How the check is scored
Each image is classified once, using the most serious issue found. A missing alt attribute is treated as the
most serious problem because the screen reader may fall back to reading the file name. Filename-like text and
keyword lists are marked as weak, and descriptions over 125 characters are flagged for review rather than
failed outright. Images with an empty alt that also declare role="presentation" or
aria-hidden="true" are accepted as intentionally decorative. The score is the percentage of images
with no flags at all, so it is a quick signal rather than a complete accessibility audit.
Limitations
The tool cannot judge whether a description is accurate, whether the surrounding paragraph already explains the image, or whether a complex image needs a longer text alternative. It also only inspects the HTML you paste; an image injected later by JavaScript will not appear. Use the report as a first pass, then review each flagged image in context and confirm the result with a screen reader or an automated audit that can render the page.
Frequently asked questions
Should decorative images have an empty alt or no alt attribute at all?
Use an empty alt attribute, written as alt="". Omitting the attribute entirely is different: many screen readers will then announce the file name. Pair the empty alt with role="presentation" or aria-hidden="true" when the image is purely decorative and you want to be explicit.
How long can alt text be?
There is no strict character limit in the specification, but around 125 characters is a common practical target because it fits in many interface contexts. If the image carries substantial information, keep the alt concise and place the full explanation in visible text next to the image or in a linked long description.
Does the checker upload my HTML?
No. The markup is parsed with the browser DOMParser and never sent to a server. Nothing is stored after you close the tab.