Alt Text Checker
Scan any webpage for missing alt text, empty alt attributes, and broken image sources — then fix them for better accessibility and SEO.
What is an Alt Text Checker?
An alt text checker is a tool to scan a webpage or URL and identify every image tag, alt attribute, and instance of missing alt text across all images on your website. It gives you a complete picture of your image accessibility and SEO coverage in seconds.
The tool parses your HTML code, reads each img tag, and evaluates its alt attribute — flagging missing image alt attributes, empty alt text on informative images, and broken image source errors like "image cannot be displayed."
Advanced checkers go further, using AI to assess the descriptive quality of existing alternative text and suggest improvements based on the image's content and page context.
Why Use an Alt Text Checker?
Two powerful reasons: accessibility and SEO — and they work together
Accessibility and SEO
Images without alt text are invisible to screen readers, leaving visually impaired users without context for your images. An alt text checker helps you identify and fix every gap so your site works for everyone.
At the same time, search engines use alt text to understand image content. Descriptive, keyword-rich alt attributes improve image search visibility and strengthen on-page SEO signals — making accessibility and SEO improvements one and the same.
Compliance and Audits
Including an image alt checker in your site audit report helps you meet W3C and web accessibility guidelines. It surfaces images without alt, decorative images that need an empty alt tag, and missing image descriptions that could put you out of compliance.
Whether you're running a routine audit or preparing an accessibility report for a client, a dedicated checker gives you accurate, actionable data fast.
Key Benefits
Everything you gain from making alt text a priority
Improve Accessibility
Identify missing image descriptions across your entire site and add descriptive text so screen readers can communicate each image's content to visually impaired users. Every image with a proper alt tag is one more element of your page that works for everyone.
Boost Image SEO
Optimize image alt text with relevant keywords and concise short descriptions so search engines can index your images accurately. Better-indexed images mean stronger rankings in image search and improved on-page relevance signals for your target keywords.
Save Time with AI
Automatically scan all images on your webpage, flag issues, and let AI generate suggested alternative text. Instead of manually reviewing hundreds of img tags, you get a prioritized list of fixes with AI-drafted descriptions ready to review and apply.
Features to Look For
What a capable image alt text checker should offer
Scan and Audit
Enter a URL to scan your webpage and check all images in one pass. A good tool produces a full site audit report listing images without alt, missing image alt attributes, empty alt text, and broken image source errors — all in one place.
AI-Powered Alt Suggestions
AI-generated descriptive text suggestions with relevance scoring and recommended keywords to add to image alt attributes. This speeds up the process of writing quality alternative text across large numbers of images on your website.
Bulk Editing and Export
Export a CSV of all image tags and alt attributes for offline review, or use CMS integrations to add alt text to images in bulk — saving hours on large sites with many images.
Decorative Image Labels
Identify decorative images and assign empty alt tags appropriately. A checker should differentiate between informative and decorative images so screen readers handle each one correctly.
Browser Extensions and Integrations
A Chrome extension lets you check alt attributes on any live page without copy-pasting HTML. CMS plugins and API access let you programmatically check image alt text as part of your publishing workflow.
Relevance Scoring
Beyond just flagging missing alt, smart checkers score existing alt text for descriptive quality and keyword relevance — helping you optimize alt text that exists but underperforms for both users and search engines.
How to Use an Alt Text Checker
A simple, repeatable process for cleaner image accessibility
Enter Your URL
Paste the webpage URL or upload raw HTML code into the tool to check alt attributes across all images on that page.
Run the Scan
The checker parses every img tag and its alt attribute, building a complete inventory of your page's images.
Review Flagged Issues
See a prioritized list: missing alt, empty alt text on informative images, broken image source errors, and low-quality descriptive text.
Write or Apply Alt Text
Use AI-suggested alternative text or write your own — descriptive, concise descriptions that capture the image's content and include relevant keywords where natural.
Update and Re-scan
Apply fixes to your HTML alt attributes or CMS, then re-scan to confirm all issues are resolved and your images are fully covered.
Best Practices for Writing Alt Text
Be descriptive and concise
Specify what the image shows and its purpose on the page. Aim for one clear, informative sentence.
Use relevant keywords naturally
Include a keyword only when it genuinely describes the image. Keyword stuffing in alt text harms both users and search engines.
Use empty alt for decorative images
Set alt="" on purely decorative images so screen readers skip them without breaking the reading flow.
Avoid "image of" or "picture of"
Screen readers already announce images as images. Jump straight to describing the content.
Examples and Use Cases
Real scenarios where an alt text checker makes a difference
Missing Alt on Product Image
The tool flags <img src="shirt.jpg"> — no alt attribute present.
AI suggestion: "blue cotton crew-neck shirt, front view" — descriptive and useful for both screen readers and image SEO.
Decorative Image in Article
A background divider image has no informational value. The checker identifies it as decorative.
Correct fix: alt="" — an empty alt attribute tells screen readers to skip it entirely.
Broken Image Source
The tool detects "image cannot be displayed" caused by a broken image source — a dead file path or moved asset.
The checker flags the img tag and URL so you can repair or redirect the source before it impacts UX and crawling.
On-Page SEO and Accessibility Considerations
Alt Text and Ranking
Search engines use alt text to understand an image's content and its relevance to the surrounding copy. Well-written alt attributes strengthen on-page SEO signals, improve image search indexing, and contribute to overall ranking — especially on pages where images are central to the content.
Texts for Images and Relevance
The best alt text aligns with both the image and the page topic. Search engines better understand your content when image descriptions are consistent with the page's subject matter and use natural keyword placement.
Avoid over-optimizing — stuffing alt attributes with keywords damages credibility with users and search engines alike. Prioritize accurate, helpful descriptions first; let relevant keywords appear only where they fit naturally.
Checking for relevance alongside missing alt coverage is what separates a thorough accessibility and SEO audit from a surface-level scan.
Pros and Cons
What to expect from automated alt text checking
Automates detection of missing image alt and empty alt text across all images on your website
Improves accessibility and image SEO simultaneously with one scan
AI-generated alternative text suggestions speed up content updates on large sites
AI suggestions may lack context-specific nuance and always require manual review before publishing
Complex page semantics can cause decorative images to be incorrectly flagged as informative
Bulk updates require CMS integration or developer effort on certain platforms
Alt Text Checker vs Other Options
How dedicated alt checking compares to manual audits and general SEO tools
Alt Text Checker vs Manual Audit
An automated image alt checker scans HTML code and image tags to flag every issue in seconds. Manual audits offer context-aware recommendations but are too time-consuming to run across an entire site regularly.
The best approach combines both: use the checker to identify and prioritize issues at scale, then apply human judgment when writing the final descriptions.
Alt Text Checker vs General SEO Tools
General SEO tools may include a basic accessibility check in site audits, but they treat images as one signal among many. A dedicated image alt tag checker focuses entirely on alt attribute quality, missing image descriptions, and broken image sources.
For teams where image accessibility and image SEO are priorities, a specialized tool delivers far more actionable detail than a generalist SEO platform.
Implementation Tips
Getting the most from an alt text checker means embedding it into your workflow — not just running it once.
Integrate into CI/CD or CMS
Include the alt text checker in your build pipeline or CMS publishing workflow so images without alt are flagged before they ever go live.
Use Semantic HTML
Keep clean img tags with descriptive alt attributes in your HTML code. Use figure and figcaption when additional context beyond the alt attribute is needed.
Review Site Audit Reports
Use the tool's site audit report to prioritize fixes. Critical missing image alt on high-traffic or high-converting pages should always be addressed first.
Alt Text Optimization Checklist
Scan all images on the page with an alt text checker
Flag missing alt, empty alt text on informative images, and broken image source errors
Generate or write descriptive and concise alt text using relevant keywords where natural
Apply updates to HTML alt attributes and re-scan to confirm
Document changes in the site audit report for future reference
Summary
An alt text checker is an essential tool to check accessibility and image SEO across every image on your website — automatically.
From flagging missing image alt attributes and broken image sources to generating AI-powered descriptions and producing a full site audit report, it helps you maintain web accessibility standards and keep your images working hard for both users and search engines.
Frequently Asked Questions
Common questions about alt text, accessibility, and image SEO
What does 'missing alt' mean?+
Missing alt means the img tag has no alt attribute at all. Screen readers and search engines cannot read a description of the image, leaving it invisible to both visually impaired users and search engine crawlers.
Is alt text required for SEO?+
Alt text is not the only ranking factor, but search engines use it to understand images. Descriptive alt attributes can improve visibility in image search results and strengthen on-page relevance — making it well worth optimizing.
Should decorative images have alt text?+
Decorative images should have an empty alt attribute (alt="") so screen readers will skip them without announcing an unhelpful "image" to the user.
Can AI write alt text?+
Yes — many alt text checkers use AI to suggest descriptive text based on the image content. However, human review is always recommended to ensure accuracy, context relevance, and natural keyword usage.
How often should I scan my site?+
Regularly — especially after large content updates, new page launches, or site migrations. These are the moments most likely to introduce images without alt or newly broken image sources.
What is an image alt tag checker?+
An image alt tag checker is another name for an alt text checker — a tool that scans your page's img tags and evaluates whether each has a valid, descriptive alt attribute. Some tools focus on detection only; others include AI suggestions and bulk editing.