Images With Missing Alt Text: How to Fix This Technical SEO Issue

Understanding Alt Text

What is alt text

Alt text (alternative text) describes images for users who cannot see them. It provides a text-based description that screen readers can announce to visually impaired users, appears when images fail to load, and helps search engines understand image content. The text is added via the alt attribute in HTML or through dedicated fields in content management systems and social media platforms. Effective alt text conveys the key information and purpose of an image in its specific context^[1][2].

Importance of alt text for accessibility

Alt text is essential for making digital content accessible to users with visual impairments, cognitive disabilities, and those with limited internet bandwidth. Screen reader users rely on alt text to understand image content, as screen readers announce file names for images lacking descriptions—creating a disruptive experience. For users with cognitive disabilities who may find images overwhelming, alt text allows them to turn off images while maintaining context. Those with slow internet connections can also grasp image content through alt text when images fail to load. Beyond accessibility, alt text is required for WCAG compliance and is frequently cited in ADA lawsuits regarding web accessibility.^[1]

SEO benefits of alt text

Alt text provides significant SEO benefits by helping search engines understand and properly index image content. When search engines crawl web pages, they cannot directly interpret images without descriptive alt text, limiting their ability to rank visual content. Properly optimized alt text helps images appear in Google Image search results and image pack displays in regular search results, creating additional organic traffic opportunities. To maximize SEO value, alt text should naturally incorporate relevant keywords while remaining descriptive and contextual—avoiding keyword stuffing which can trigger search engine penalties.^[2][3]

Common Alt Text Issues

Missing alt attributes

Missing alt attributes occur when images lack the HTML alt property entirely, rather than having an empty alt value. This creates accessibility barriers since screen readers will either skip the image completely or read out the file name, providing no context about the image’s content or purpose. Common causes include content management systems that don’t enforce alt attributes, manual HTML coding without accessibility considerations, and automated content imports that strip alt properties. As mentioned above, missing alt attributes can trigger accessibility compliance violations under WCAG guidelines, which require alt text for all non-decorative images.^[4]

Empty alt attributes

Empty alt attributes (alt=””) serve a distinct purpose from missing alt attributes. While missing alt attributes cause screen readers to read file names or skip images entirely, empty alt attributes deliberately tell screen readers to ignore decorative images that don’t convey meaningful content. Empty alt attributes should only be used for purely aesthetic elements like background patterns, divider lines, or mood-setting photos that don’t contribute to understanding the page content.^[5] This approach streamlines the experience for screen reader users by avoiding unnecessary descriptions while ensuring they receive all essential visual information.^[6]

Non-descriptive alt text

Non-descriptive alt text creates accessibility barriers by failing to meaningfully convey image content and context. Common examples include generic labels like ‘image’ or ‘photo’, file names (img001.jpg), and vague descriptions that omit key details (‘a person standing’). Auto-generated alt text often produces inadequate descriptions like ‘picture containing outdoor, person’ that miss the image’s purpose and emotional context. As discussed earlier, poor alt text reduces SEO value since search engines cannot properly index and contextualize the visual content. The solution requires writing specific, contextual descriptions that explain both what an image shows and why it matters.^[7]

Best Practices for Alt Text

Writing effective alt descriptions

Writing effective alt text requires balancing descriptive detail with concise clarity. Focus on conveying the key information and purpose an image serves in its specific context. For a product photo on an ecommerce site, describe the distinguishing features and specifications. For that same image in a blog post about photography techniques, describe the composition and lighting choices. When writing alt text for charts and data visualizations, summarize the key trends or findings rather than describing every data point. The goal is to provide equivalent access to the image’s meaning and function, not just describe its visual appearance.^[8][9]

When to use empty alt attributes

As mentioned above, empty alt attributes (alt=””) serve a specific purpose—they tell screen readers to deliberately skip decorative images that don’t convey meaningful content. Use empty alt attributes only for purely aesthetic elements like background patterns, divider lines, borders, bullet points, and decorative icons that add visual appeal but no information. The key test is whether removing the image would impact understanding—if it would, the image needs descriptive alt text.

Length and formatting guidelines

Alt text should be concise while providing sufficient detail—generally 125 characters or less for standard images. For complex images like infographics, limit descriptions to 150-250 characters focused on key information. Format alt text as grammatically complete phrases or sentences, capitalizing the first letter and ending with appropriate punctuation. Avoid redundant phrases like ‘image of’ or ‘picture showing’ since screen readers already announce the element type.^[10]

Identifying Missing Alt Text

Manual inspection methods

Manual inspection of missing alt text can be done through browser developer tools and screen readers. Using browser dev tools, right-click any image and select ‘Inspect’ or ‘Inspect Element’ to view the HTML code and check for the alt attribute. The HTML will show either a missing alt attribute, an empty alt attribute, or the actual alt text description. For bulk checking, enable your operating system’s built-in screen reader and navigate through page images—the screen reader will announce file names for images missing alt text and read out any existing descriptions. Regular manual checks help catch issues that automated tools might miss, particularly for dynamically loaded images or those embedded through content management systems.^[11]

Automated scanning tools

Automated scanning tools streamline the process of finding missing alt text across websites. These tools can crawl entire sites to identify both missing alt attributes and empty alt text.^[12] They provide detailed reports showing which pages contain problematic images and allow bulk export of findings for remediation.

Browser extensions for alt text checking

Browser extensions provide an efficient way to check alt text while browsing websites. Popular options display alt text overlays on images and highlight those missing descriptions.^[13] Some extensions focus on social media, showing missing alt text on platforms like Twitter and optionally blocking post submission until descriptions are added.^[14] The most effective extensions combine immediate visual feedback with detailed reporting capabilities that help prioritize fixes based on impact.^[15]

Implementing Alt Text Solutions

Bulk alt text updates

Several tools and methods enable efficient bulk updates of missing alt text across websites. Content management systems often include built-in bulk editing interfaces in their media libraries where multiple images can be selected and updated simultaneously. For large-scale updates, automated tools can use AI to generate contextual descriptions—though these should be reviewed for accuracy and relevance before implementation.^[16] Database-level updates through SQL queries offer another approach for technical teams to modify alt attributes across many images at once, particularly useful for custom CMS implementations.

CMS-specific solutions

Different content management systems offer specialized tools for managing alt text at scale. Some include validation that flags common alt text issues like redundant phrases, file extensions in descriptions, and text exceeding character limits.^[17] For maximum effectiveness, CMS alt text tools should enforce character limits, prevent duplicate descriptions across similar images, and integrate with existing editorial workflows. Beyond automated tools, CMS platforms should provide clear guidelines and examples to help content creators understand proper alt text usage in different contexts.^[18]

Maintaining alt text compliance

Maintaining alt text compliance requires ongoing monitoring and systematic processes. Regular automated scans should check for new missing or inadequate alt text, with reports sent to content owners for remediation.^[1] Organizations can maintain compliance by establishing clear ownership of alt text quality, setting measurable improvement targets, and treating accessibility as an ongoing program rather than a one-time project.^[19]