Alt Text Checker: Find Missing Image Alt Text

This alt text checker reads HTML you paste in and lists every image it finds, marking each one as missing alt, empty (decorative), worth a second look, or fine, with a count of each at the top. It checks img elements, image buttons, image map areas and SVG graphics marked as images.

It works on the page source rather than a web address, because browsers do not let one site read another site's pages. Copying the source takes about ten seconds, and the steps are below. Everything happens in your browser, so private or unpublished pages are safe to check.

Quick facts

Input
Pasted HTML: a whole page or a snippet
Finds
img, input type=image, area links and svg role=img
Results
Must fix, to review, decorative and fine, with counts
Copy the source
Ctrl+U on Windows, Option+Command+U on a Mac
Privacy
Nothing leaves your browser
Limit
It flags patterns; only a person can judge if a description is right

Checking a page with the alt text checker

Open the page you want to test. Any public or private page works, including a staging copy.
Press Ctrl+U (Windows, Linux, ChromeOS) or Option+Command+U (Mac; Firefox on a Mac uses Command+U). You can also right click an empty part of the page and choose View page source.
In the source tab, select all with Ctrl+A or Command+A and copy.
Paste into the box labelled "Paste the page HTML" and press Check images.
Read the summary line, then the table. Each row shows the element, its file, its alt value and a result.

Worked example

Say you paste this snippet from a café site:

<a href="/"><img src="logo.svg" alt=""></a>
<img src="hero.jpg" alt="IMG_2231.jpg">
<img src="latte.jpg" alt="Image of a latte">
<img src="swirl.svg" alt="">
<img src="map.png">

The checker reports five images: 2 must fix, 2 to review, 1 decorative, 0 fine. The linked logo fails because its alt is empty and the link has no other text, so it has no name at all. The map has no alt attribute. The hero looks like a file name, and the latte starts with "Image of". The swirl divider is correctly decorative.

Why the checker cannot load a website by address

A tool on one website is not allowed to read pages from another website through your browser. This safety rule, part of how browsers keep sites apart, stops a page you visit from quietly reading your email or bank pages. So a free checker that runs fully in your browser needs you to hand it the HTML.

One catch: View source shows the HTML as first sent by the server. If images are added later by scripts, as in many single page apps and product galleries, they may be missing from the source. In that case, open developer tools (F12), right click the <html> element in the Elements panel, choose Copy, then Copy outerHTML, and paste that instead. It contains the page as it is right now.

Whole site crawlers exist, run as browser extensions or desktop apps. You can filter the W3C evaluation tools list by feature to find one.

What each result label means

Checker labels and what to do
Label	Group	Meaning and action
Missing alt	Must fix	No alt attribute at all. Some screen readers then announce the file name. Write a description, or use `alt=""` if decorative.
Empty alt inside a link or button with no text	Must fix	The link or button has no accessible name. Describe its destination or action.
Empty alt, treated as decorative	Decorative	Correct if the image adds nothing. Check that it really is decoration.
Looks like a file name	To review	Values like `DSC_0042` or `banner-final.png`. Replace with a description.
Starts with "image of" or similar	To review	Drop the phrase; screen readers already say "image".
Too vague	To review	Single words like "photo", "logo" or "banner" tell the listener nothing.
Long (number of characters)	To review	Over 150 characters. Shorten it and move detail into the page.
Same alt used on several images	To review	Often a template default. Fine for repeated icons with the same job, wrong for different photos.
Looks fine, read it in context	Fine	No pattern problem. Still read it next to the image.

How to check alt text of an image on a website without a tool

Sometimes you only need to inspect one picture. These methods work in any desktop browser:

Inspect the element. Right click the image and choose Inspect. Developer tools open with the img tag highlighted, and you can read its alt value directly.
Turn images off. In browser settings you can block images for a site. Alt text then appears where pictures were, which shows quickly how the page reads without them.
Hear it as users do. Turn on a screen reader, jump from graphic to graphic and judge each description by ear. This is the best way to judge whether alt text makes sense.

Hovering over an image does not show its alt text in current browsers. The tooltip you sometimes see comes from the title attribute, which is a different thing and is not a substitute for alt.

Alt text viewer extensions

An image alt text viewer extension for Chrome, Edge or Firefox draws each image's alt value on top of the page, or lists every image in a side panel. They are quick for spotting gaps while you browse, and they work on pages built by scripts. Their limits are the same as this tool's: they flag patterns, but cannot know whether "Team photo" is good enough for that page.

If you check sites often, combine an extension for browsing with this checker for a clean, countable report you can paste into a ticket.

Fixing missing alt text once you find it

Where you add the fix depends on how the site is built:

Hand coded HTML: add the alt attribute to the img tag.
WordPress: fill in "Alternative Text" in the image block settings or in the Media Library. Text set in the Media Library is not always copied into images already placed in posts, so check both.
Shopify: open the product, select the image in the media area and edit its alt text there.
Theme templates: if a logo or icon in the header fails on every page, fix it once in the template.

The step by step screens for these and other tools are on how to add alt text. For the words themselves, follow how to write alt text, or draft one with the alt text generator.

What no automatic checker can tell you

A checker sees text, not meaning. "Woman smiling" passes every pattern test, yet on a page about a product launch it may hide the fact that she is holding the product. Across accessibility as a whole, automated rules spot perhaps a third of real barriers, and whether a description is apt lies outside their reach.

Use the counts to find gaps fast, then have a person read each description beside its image. Our pages on what alt text is and alt text examples help reviewers agree on what good looks like.

Questions people ask

How do I check the alt text of an image?

Right click the image and choose Inspect to read its alt attribute in developer tools. To check a whole page, copy its source with Ctrl+U and paste it into this checker.

Why does hovering not show alt text?

Modern browsers do not show alt text on hover. The tooltip some images show comes from the title attribute. Use Inspect, this checker or a screen reader to see the alt value.

Is there an alt text checker Chrome extension?

Yes, several extensions overlay alt text on images or list images that lack it. They are handy while browsing; this page is useful when you want a counted report from pasted HTML without installing anything.

Can this tool scan my whole website?

No, it checks the HTML you paste, one page or snippet at a time. For a full site, check your templates first, since most repeated problems come from them, then sample key pages.

What counts as missing alt text?

An img element with no alt attribute at all. An empty alt is not missing; it marks the image as decorative, which is correct when the image adds no information.

Is the HTML I paste stored anywhere?

No. The check runs in your browser and nothing is sent to a server, so you can safely paste pages from staging or an intranet.