Alt Text Generator

What is Alt Text?

Alt text (alternative text) is a written description added to an image's HTML tag. It serves as a text replacement when images cannot be displayed and is read aloud by screen readers for visually impaired users. Good alt text is essential for web accessibility and SEO.

How This Tool Generates Alt Text

This tool analyzes your image entirely in the browser using the Canvas API. It extracts visual properties like dimensions, aspect ratio, dominant colors, brightness, and file metadata. Combined with the context you provide (informative, functional, decorative, or complex), it generates structured alt text following WCAG 2.1 guidelines.

Types of Images

• Informative: Convey information not available in surrounding text. Alt text should describe the content and purpose.
• Functional: Used within links or buttons. Alt text should describe the action, not the image appearance.
• Decorative: Add visual interest but convey no information. Use empty alt text (alt="").
• Complex: Charts, graphs, diagrams. Provide a short alt text summary and a longer description nearby.

Best Practices

• Keep alt text under 125 characters when possible (screen reader compatibility)
• Don't start with "image of" or "picture of" — screen readers already announce it as an image
• Be specific and concise: describe what matters in the current context
• For decorative images, use alt="" (not omitting the attribute)
• Include text visible in the image
• For complex images, use aria-describedby to link to a longer description

WCAG Requirements

WCAG 2.1 Success Criterion 1.1.1 (Non-text Content, Level A) requires all non-text content to have a text alternative that serves the equivalent purpose. This is the most fundamental accessibility requirement and applies to all images on the web.

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.