Picture someone using a screen reader to move through your homepage. The software reads the headline, the intro, the navigation, and then it reaches your hero image and says, simply, "image." No description, no context, just a dead end where a thousand-word picture was supposed to be. Now picture Google's crawler arriving at the same image: it sees a file it can't interpret and moves on, and your carefully chosen product shot contributes nothing to how the page is understood or ranked.
That's what missing alt text costs you, twice over. It locks out the visitors who depend on it and it hides your images from search at the same time. The catch is that nothing on the visible page looks wrong, the images load and display perfectly, so the gap stays invisible until an accessibility audit or a stalled image-search ranking surfaces it. This guide covers how to find images missing alt text across your whole site, so you close the gap on purpose rather than by accident.
What alt text is, and what "missing" means
Alt text is a short written description attached to an image in the HTML, like this:
<img src="team-photo.jpg" alt="Our design team at the 2026 offsite">
It does two jobs. Screen readers read it aloud so people who can't see the image still get its meaning, and search engines use it to understand what an image shows, which is how images earn their place in image search. "Missing" usually means the alt attribute isn't there at all, but it also covers the empty-but-careless case and the unhelpful case, a product photo with alt="" or alt="image123.jpg" technically has an attribute but communicates nothing.
One nuance worth knowing: a genuinely decorative image, a divider line or a background flourish, is supposed to have an empty alt="" so screen readers skip it. The goal isn't alt text on literally everything. It's a meaningful description on every image that carries meaning, and a deliberate empty one on those that don't.
Why missing alt text matters
It's an accessibility barrier (and often a legal one)
For people who use screen readers, alt text is the only way an image exists at all. Without it, a meaningful photo, chart, or infographic simply vanishes from their experience of the page. This is also the most common single failure flagged in automated accessibility testing, and it maps directly to WCAG 2.1, the standard much accessibility law points to. For many organizations, missing alt text isn't only a courtesy gap, it's a compliance risk.
It hides your images from search
Search engines can't see what's in a photo the way a person can. Alt text is the main signal they use to understand and index an image, so a picture with no description is a picture that can't rank in image search and contributes little to the page's topical relevance. For sites where visuals drive discovery, product catalogs, portfolios, recipe and travel content, that's real traffic left on the table.
It's a sign of a rushed process
Images get uploaded in a hurry, and the alt field is the easiest thing to skip. So a page full of undescribed images usually points to other things that got skipped too: a missing meta description, a thin title, a placeholder that never got replaced. Finding the gaps in your alt text often surfaces the wider corner-cutting around it.
How to find images missing alt text
There are a few ways to do this, from manual checks to scanning the whole site at once. The right one depends on how many images and pages you're dealing with.
1. View the page source or inspect elements (free, one page at a time)
On any page you can right-click an image, choose "Inspect," and look at the <img> tag for an alt attribute. Or view the full page source and scan the image tags. It's accurate and free, but it only covers the page in front of you and it's slow going on anything image-heavy. Checking a whole site this way isn't practical.
2. Browser accessibility extensions (free, page-level)
Accessibility checker extensions will scan the current page and flag images with no alt attribute, often highlighting them visually. Handy for spot-checking a single landing page before it ships. The limit is the same as above: one page at a time, with no view across the whole site.
3. An on-demand quality controller (the whole site, at once)
This is the approach that fits the real job: scan every page in one pass and get back a list of exactly which images, on which pages, are missing alt text, with nothing to inspect by hand.
Steterly does this directly. It crawls every page, checks each image, and flags the ones missing an alt attribute, so you get a clear, page-by-page list to work from. Unlimited image alt checks are included even on the free plan, and on the Studio and Agency plans the same crawl also runs a full automated WCAG 2.1 Level AA accessibility scan, so missing alt text shows up alongside other critical barriers like unlabelled form fields, broken ARIA roles, and buttons with no accessible name. You can start with a free scan of up to 50 pages, no credit card required.
Because Steterly renders each page in a headless browser before reading it, it catches images loaded dynamically by JavaScript, the kind a simple scraper would miss entirely. And since it's already crawling everything, the same scan turns up the slips that travel with missing alt text: missing meta descriptions, broken links, dead images, typos, duplicate or missing H1 tags, placeholder text, and Core Web Vitals issues. One scan, the whole picture.
How to write good alt text once you find the gaps
Finding the missing ones is most of the work. Writing them well comes down to a few principles.
- Describe the meaning, not just the contents. Ask what the image is doing on the page. "Barista pouring latte art at our downtown cafe" beats "coffee," because it carries the context a sighted visitor gets at a glance.
- Keep it concise. A sentence or so is usually plenty. Screen readers read the whole thing aloud, so a paragraph-length description becomes a chore to listen to.
- Skip "image of" and "photo of." Screen readers already announce that it's an image, so those words just add noise. Jump straight to the description.
- Work in keywords only where they fit naturally. Alt text helps image SEO, but it's a description first. Stuffing keywords reads badly to screen-reader users and can look like spam to search engines.
- Use empty alt for purely decorative images. A divider, a background texture, or an icon that repeats adjacent text should get
alt=""so screen readers skip it rather than announcing clutter.
How to stop the gaps from coming back
Clearing them out once is satisfying. Having to do it every month as new images pile up is not. A few habits keep it handled:
- Make alt text a required step when uploading. Most CMSs have an alt field right in the media library. Treat filling it in as part of adding the image, not an afterthought.
- Scan at the moments that matter. Before a launch, after a content push, and on a regular cadence. For the full routine, see our pre-launch website audit checklist.
- Audit after migrations. Alt text is often lost when images are re-imported during a redesign or CMS move. Re-scan right after to catch what didn't carry over.
- Brief everyone who publishes. If multiple people add content, a one-paragraph standard for what good alt text looks like keeps quality consistent and gaps rare.
Frequently asked questions
How do I find all images missing alt text at once?
Inspecting elements or using a browser extension only covers one page at a time. To check a whole site at once, use a crawler that examines every image on every page. Steterly scans your entire site in one pass and flags each image missing an alt attribute, page by page.
Does missing alt text hurt SEO?
Yes, for images specifically. Search engines rely on alt text to understand what an image shows, so an image without it can't rank well in image search and adds little to the page's topical relevance. It won't tank your overall rankings on its own, but it's missed visibility, especially for visual content.
Is alt text legally required?
It depends on your jurisdiction and the rules that apply to your organization, and this isn't legal advice. That said, missing alt text is one of the most common failures against WCAG 2.1, the accessibility standard a great deal of accessibility law references, so for many sites it's treated as a compliance issue, not just a best practice.
Should every image have alt text?
Every meaningful image should. Purely decorative images, dividers, background textures, icons that just repeat nearby text, should have an empty alt attribute (alt="") so screen readers skip them. The goal is a useful description on everything that carries meaning, and a deliberate empty value on everything that doesn't.
What makes good alt text?
A concise description of what the image means in context, usually a sentence or less. Skip "image of," since screen readers already announce that it's an image. Include a keyword only where it fits naturally. The test: if the image vanished, would your alt text give someone the same understanding a sighted visitor gets?
Can I find missing alt text for free?
Yes. Steterly includes unlimited image alt checks on its free plan, so a free scan of up to 50 pages (no credit card) flags every image missing alt text across your site. The full automated WCAG accessibility scan, which covers other barriers like unlabelled forms and broken ARIA roles, is on the Studio and Agency plans.
Catch the slips before your visitors do
Missing alt text doesn't announce itself. The page looks perfect, the images display fine, and the gap stays hidden until a screen-reader user hits a wall or your images quietly fail to show up in search. Both audiences are counting on a description that isn't there. The fastest way to fix that is to scan the whole site at once and write alt text for whatever comes back.
Steterly is the quality controller for that job. Start with a free scan (no credit card required) and get a clear list of every image missing alt text, alongside the broken links, typos, and missing tags across your site, so you can close the gaps before anyone, or any crawler, runs into them.