Free Image Alt Text Checker
Enter a URL to find all images on the page that are missing alt text - a common accessibility and SEO issue.
What this alt text checker checks
This free alt text checker fetches the page you enter and reads the alt attribute on every image with a src in its HTML. It flags images where the alt attribute is absent entirely or contains only whitespace, which is what the "Images missing alt text" result reports. It does not flag an empty alt (alt=""), because an empty alt is the correct, valid way to mark a purely decorative image so screen readers skip it.
Under that result you also get an itemised review list grouped by issue type, so you have something to work through rather than just a count: images with no alt, a filename used as the alt (for example "IMG_4392.jpg"), alt text over 125 characters, and the same alt text shared by more than one image. Each row shows the image source and its current alt. Only a missing alt changes the result to a warning; the other three are suggestions to review.
It works on WordPress, Webflow, Shopify, Squarespace and any other platform, because it reads the HTML your server sends rather than plugging into your CMS. It does not run JavaScript, so images that a script injects after the page loads will not appear in the results.
Alt tag vs alt text: is there a difference?
Not really. Most people say "alt tag", but technically alt is an attribute on the img tag, not a tag of its own: in <img src="team.jpg" alt="Our support team at their desks">, the alt attribute holds the alt text. "Alt tag", "alt attribute", "alt text" and "alternative text" all describe the same thing.
Whatever you call it, this checker lists every image whose alt is missing, plus the ones worth a second look.
How to write good alt text
Alt text is what a screen reader announces in place of an image, and it is how search engines understand what an image shows. Describe the image the way you would to someone who cannot see it, in the context of the page:
- Be specific and concise: aim for roughly 125 characters or fewer, which is where this tool starts listing alt text as too long. Describe what matters, not every detail.
- Do not start with "image of" or "picture of": screen readers already announce that it is an image.
- Never use the filename: "DSC_0042.jpg" tells nobody anything, and some CMS uploads fill the alt from the filename by default.
- Skip keyword stuffing: write for a human. One natural mention of a relevant term is fine; a list of keywords reads as spam and helps no one.
- Mark decorative images with alt="": if an image is purely decorative (a divider, a background flourish), an empty alt tells assistive tech to skip it.
Fixing alt text on WordPress and Webflow
On WordPress, set alt text in the Media Library or in the block settings for each image; the Alternative Text field sits in the block sidebar when an image is selected. Updating it in the Media Library sets the default for future uses, but images already placed in posts keep the alt they were inserted with, so check those pages too. Featured images, and anything else your theme renders straight from the attachment, read the Media Library alt directly, so those do update everywhere.
On Webflow, set alt text on the image itself in the Assets panel (the settings cog, then the Descriptive field), and every use of that image inherits it; choose Decorative there for a purely decorative image. To change one instance, select the image, open Image settings and pick Custom description or Decorative from the Alt text dropdown. CMS images get their own alt text only when you add a plain text field to the collection and bind the image's Alt text to it in Element settings. For the full walkthrough, read the alt text guide.
From one page to a full audit
This tool checks one page and one thing. A full free audit crawls up to 10 pages of your site, lists every unique image missing alt text across all of them, and runs all 40 checks: broken links, titles and meta descriptions, Core Web Vitals, structured data, security headers and AI Visibility. It also writes one AI fix instruction for your highest-impact issue. Pro adds an AI fix for every issue, a PDF report and a crawl of up to 100 pages.
If you are weighing up which audit tool to use, our comparison of the best free website audit tools sets out what each one checks for free.
Frequently asked questions
Is this alt tag checker free?
Yes. It is free, needs no account, and does not store the URLs you check (if you ask us to email you the results, we keep your email address). Enter a public URL and you get the result in seconds. There is a fair-use limit of 15 checks per hour.
How do I check the alt text on a webpage?
Enter the page URL above and run the check. You get a list of every image missing an alt attribute, plus images using a filename as the alt, overly long alt text and duplicated alt text. To check by hand instead, right-click an image, choose Inspect, and look for the alt attribute on the img element.
Are decorative images with alt="" flagged?
No. An empty alt="" is the correct way to mark a decorative image so screen readers skip it, so it is treated as valid. Only an image with no alt attribute at all, or an alt containing only spaces, is reported as missing.
Why does the checker list some alt text as too long?
Alt text over 125 characters is tiring to listen to on a screen reader, so the checker lists it for you to review. It is a suggestion only: long alt text never turns the result into a warning. If an image genuinely needs more explanation, such as a chart, put the detail in a caption or the surrounding text.
Does it check alt text that JavaScript adds?
No. It reads the HTML the page serves without running scripts, so images or alt text added by JavaScript after load are not seen. Google does render JavaScript, so a script-injected image can have alt text Google sees but this tool does not. The full audit renders pages in a real browser and catches those.
What does the full audit add over this tool?
This tool checks alt text on a single page. A full free audit crawls up to 10 pages, runs all 40 checks with full detail and adds one AI fix. Pro adds an AI fix for every issue, a PDF report and up to 100 pages. Learn more in the alt text guide.