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Alt Text Checker

Paste your HTML to find images missing alt text, detect empty alt attributes on non-decorative images, and identify overly long descriptions.

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Enter a URL or paste HTML above to analyze your images.

How to Use Alt Text Checker

  1. 1

    Paste your HTML

    Copy the HTML source code from the page you want to check and paste it into the input area.

  2. 2

    Click Check Alt Text

    Press the button to scan all <img> tags and evaluate their alt attribute status.

  3. 3

    Review the summary

    See how many images were found, how many have alt text, and how many are missing it.

  4. 4

    Fix flagged images

    For each image flagged as missing or problematic, add or improve the alt text in your source code.

Frequently Asked Questions

Alt text (the alt attribute on <img> tags) provides a text alternative for images. Screen readers read this text aloud to blind and low-vision users. Without alt text, screen readers may announce the image file name or skip it entirely, leaving users without critical information. WCAG Success Criterion 1.1.1 (Non-text Content) requires all non-decorative images to have meaningful text alternatives.

Images that are purely decorative and convey no information should have an empty alt attribute (alt=""). This tells screen readers to skip the image entirely. Examples include background patterns, decorative dividers, and icons that appear next to text that already conveys the same meaning. Adding role="presentation" alongside empty alt makes the decorative intent explicit.

Alt text should be concise and descriptive, generally under 125 characters. Screen readers handle long alt text differently: some read it all at once without pausing, making very long descriptions difficult to follow. For complex images like charts or infographics, use a brief alt text and provide a longer description in surrounding text or via a longdesc attribute.

Good alt text describes the content and function of the image in context. Avoid starting with 'image of' or 'picture of' since screen readers already announce it as an image. Be specific: instead of 'person', write 'woman presenting quarterly results to a team'. Consider what information the image conveys that the user would miss without it.

No. All processing happens locally in your browser using JavaScript. Your HTML never leaves your device. This makes it safe to use with client code, proprietary content, or any sensitive markup.

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Why Image Alt Text Is Critical for Web Accessibility

Images convey information that text alone cannot. Photographs show context and emotion. Charts communicate data relationships. Icons signal functionality. When these images lack text alternatives, the information they carry becomes invisible to anyone who cannot see them. This includes blind users who rely on screen readers, users with low bandwidth who have images disabled, and search engine crawlers that index your content. Alt text bridges this gap by providing a text equivalent that describes the image's content and purpose.

WCAG Requirements for Images

WCAG 2.2 Success Criterion 1.1.1 (Non-text Content) is a Level A requirement, the most basic level of conformance. It states that all non-text content must have a text alternative that serves the equivalent purpose. For images, this means every <img> element must have an alt attribute. The content of that attribute depends on the image's purpose: informative images need descriptive alt text, functional images (like buttons and links) need alt text describing the function, and decorative images need empty alt text (alt="") to be properly skipped by assistive technology.

Types of Images and Their Alt Text Needs

Informative images convey content that is not available in the surrounding text. These need alt text that describes what the image shows. A photo of a product should describe the product. A headshot should identify the person. The alt text should convey the same information a sighted user would gain from the image.

Functional images are used as links or buttons. Their alt text should describe the action or destination, not the image itself. A magnifying glass icon used as a search button should have alt text like "Search," not "magnifying glass icon." Similarly, a company logo that links to the homepage should say "Company Name - Home" rather than describing the logo's visual design.

Decorative images add visual interest but convey no information. Background patterns, ornamental borders, and icons that duplicate adjacent text are decorative. These should have empty alt text (alt="") so screen readers skip them. Without the empty alt attribute, screen readers will try to announce the file name, which is meaningless noise for the user.

Complex images like charts, graphs, and infographics contain data that cannot be adequately described in a short alt attribute. These need a brief alt text summarizing the image's purpose along with a detailed description provided elsewhere, either in the surrounding text, a linked page, or through a longdesc attribute.

Common Alt Text Mistakes

The most frequent mistake is simply omitting the alt attribute entirely. This causes screen readers to announce the image file path or URL, which is confusing and unhelpful. Another common error is using generic text like "image" or "photo" that provides no useful information. Stuffing keywords into alt text for SEO purposes also harms accessibility by forcing screen reader users to listen to irrelevant text. Finally, developers sometimes add alt text to purely decorative images, cluttering the screen reader experience with unnecessary announcements.

Writing Effective Alt Text

Think about what the image communicates to a sighted user and express that in words. Be concise but specific. Do not start with "image of" or "picture of" because screen readers already announce the element as an image. Consider the surrounding context: if the text around the image already describes its content, a shorter alt text or even an empty alt may be appropriate to avoid redundancy. Test your alt text by reading it aloud. If the text conveys the image's meaning without seeing the image, it is effective.

How This Tool Helps

This alt text checker scans your HTML and identifies every <img> element. It flags images with no alt attribute as errors, warns about empty alt on non-decorative images, and highlights alt text that exceeds the recommended 125-character limit. Each result shows the image source, alt text content, character count, and a clear status indicator. Use this tool during development to catch alt text issues before they reach production, and combine it with our other accessibility tools for a comprehensive audit.