Image Alt Text Checker

Paste HTML to audit all images for missing, empty, or proper alt attributes. Get an instant accessibility and SEO image report with an alt-text score.

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Frequently Asked Questions

Alt text (the alt attribute on <img> tags) serves two purposes. First, it provides a text description for screen readers, making images accessible to visually impaired users. Second, search engines use alt text to understand what an image depicts, which influences rankings in Google Image Search and provides additional keyword context for the page. Pages with descriptive, keyword-relevant alt text typically rank better for image-related queries.
Missing alt means the alt attribute is absent entirely — e.g. <img src="photo.jpg">. This is an accessibility violation and leaves search engines with no text description. Empty alt (alt="") is intentional: it tells screen readers to skip the image and signals to search engines that the image is decorative. Empty alt on decorative images is correct practice; missing alt is always an error.
Alt text should be concise and descriptive — typically under 125 characters. Many screen readers truncate alt text at around 125 characters. Focus on what the image shows and how it relates to the surrounding content. Avoid keyword stuffing: "red running shoes" is good; "buy red running shoes cheap discount shoes sale" is not. Purely decorative images should use an empty alt attribute.
Google uses alt text as a signal to understand image content, so missing alt text means Google has less context — potentially impacting image search rankings. For regular web search, the effect is indirect: missing alt text can result in poor accessibility scores in Core Web Vitals Lighthouse audits (Accessibility score), which Google acknowledges as a page experience factor.
The "Long" badge flags alt text exceeding 125 characters. While not technically wrong, very long alt text is often truncated by screen readers and can appear like keyword stuffing to search engines. Best practice is to keep alt text under 125 characters. If you need a longer description, use a longdesc attribute or visible caption instead.

About This Image Alt Checker

This free SEO tool parses raw HTML and audits every <img> element for alt attribute status. Images are classified as missing alt (no attribute at all), empty alt (decorative), or has alt text. An alt-text score shows what percentage of non-decorative images have proper descriptions.

When to use this tool

  • Accessibility audits to fix WCAG 1.1.1 failures
  • Pre-publishing image SEO checks on blog posts or product pages
  • Identifying images that need descriptive alt text before site migrations
  • Verifying CMS-generated HTML includes alt attributes on all images

What makes good alt text

  • Describes the image's content and context accurately
  • Under 125 characters in length
  • Includes a target keyword naturally where relevant
  • Does not begin with "image of" or "picture of" — screen readers announce this already
  • Decorative images use alt="" (empty string, not missing)

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Alt text for accessibility and alt text for SEO look identical in HTML — but the goals that inform them pull in different directions. Here's where they diverge: context-dependency (the same image needs different alt text in different contexts), keyword stuffing (which fails the "read it aloud" test), the functional images where SEO keyword inclusion is actively wrong, and the complex images where neither alt text alone nor SEO keywords capture enough information.
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Alt Text and the Law: How WCAG 1.1.1 Became Central to ADA Lawsuits and the European Accessibility Act
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