What is an Alt Text Checker?
An alt text checker is an accessibility tool that analyzes images on a webpage to find missing, empty, or poorly written alt attributes — helping you ensure your content is accessible to screen reader users and compliant with WCAG standards.
Alt text (alternative text) is a text description added to images via the alt attribute. It's read aloud by screen readers for visually impaired users, displayed when images fail to load, and used by search engines to understand image content. Proper alt text is legally required under ADA and WCAG accessibility guidelines.
Our alt text checker scans any URL and flags images with missing alt attributes, empty alt text on meaningful images, filename-based descriptions, redundant phrases like "image of," alt text that's too long, and linked images that don't describe their destination.
What the Tool Checks
Missing Alt Attributes
Images without an alt attribute at all. Every image must have an alt attribute — even if it's empty for decorative images.
Empty Alt on Meaningful Images
Images with alt="" that appear to convey meaning. Empty alt is correct for purely decorative images, but if the image is linked or has context, it needs a description.
Filename-Based Alt Text
Alt text that's just a filename like "image001.jpg" or "IMG_1234". Screen readers will read this literally, making no sense to users.
Redundant Phrases
Alt text starting with "image of", "photo of", "picture of", etc. Screen readers already announce "image" before reading alt text, so these phrases are redundant.
Alt Text Too Long
Alt text over 150 characters. WCAG recommends keeping alt text concise. If detailed information is needed, use a caption or longer description in the surrounding text.
Unclear Linked Images
Linked images with generic alt text like "click here" or "button". When images are links, the alt text should describe where the link goes, not just the image content.
WCAG Alt Text Guidelines
Success Criterion 1.1.1: Non-text Content (Level A)
All non-text content (images, videos, audio) must have a text alternative that serves the equivalent purpose. This is a Level A requirement — the most basic accessibility standard.
Best Practices:
- ✓Be specific and descriptive — "Golden retriever puppy playing in grass" not "dog"
- ✓Keep it concise — aim for under 150 characters
- ✓Don't start with "image of" or "photo of" — redundant with screen readers
- ✓For decorative images, use
alt=""(empty string) - ✓For linked images, describe the link destination, not just the image
- ✓Include text in images if relevant (e.g., "Stop sign" or "Logo: Company Name")
Why Alt Text Matters
Accessibility
15% of the global population has some form of disability. Screen readers rely entirely on alt text to convey image content to blind and visually impaired users.
Legal Compliance
ADA Title III requires websites to be accessible. Lawsuits for accessibility violations are common. Proper alt text is a basic, legally required accessibility feature.
SEO Benefits
Search engines use alt text to understand image content. Well-written alt text improves image search rankings and helps search engines index your pages accurately.
Frequently Asked Questions
When should I use alt="" (empty alt text)?+
Use alt="" only for purely decorative images that convey no information — like background patterns, spacers, or decorative borders. If an image adds meaning, context, or information, it needs descriptive alt text.
What's the difference between alt text and image captions?+
Alt text is hidden text read by screen readers and shown when images fail to load. Captions are visible text displayed below images for all users. Alt text describes what's in the image; captions provide context, attribution, or additional information.
How do I write good alt text for complex images like charts?+
For complex images (charts, graphs, diagrams), provide a short alt text summarizing the main point, then include a longer description in the surrounding text or use longdesc or aria-describedby. Example: alt="Bar chart showing revenue growth 2020-2024" with details in a table or paragraph below.
Does this tool fix alt text automatically?+
No. This tool identifies issues but doesn't automatically fix them. Alt text must be written by humans who understand the image content and context. Use the checker to find problems, then manually add or improve alt text in your CMS or HTML.
Can I check private or password-protected pages?+
No. The tool can only check publicly accessible URLs. For private pages, use browser extensions or manual inspection with your browser's DevTools (right-click → Inspect).
Ready to check your website's accessibility? Use the free alt text checker above to scan any URL for image accessibility issues.