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Image SEO Checker

Free, no signup. Audit image SEO signals visible in raw HTML. Rendered dimensions, real LCP, transfer sizes, and AI alt-text generation are shown honestly as unavailable in this tool.

Built by Patrick Stox

Checks run from our server; we fetch the URL you enter and don't keep the results. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.

Feedback
Report a bug

Found something broken in Image Seo Checker? Let us know what happened — this goes straight to a private triage queue, not a public list.

What will be sent 
 No tool inputs, uploads, pasted source, complete results, query parameters, or URL fragments are attached automatically. You can edit or remove the selected passage above. Browser and anti-abuse metadata is processed for spam prevention. 
  
 
  
 
 
  
 
 
  
 
 
Sample report
Illustrative example — based on the markup shown
<img src="hero.jpg">
<img src="divider.svg" alt="" loading="lazy">
<img src="chart.webp" alt="Quarterly traffic by channel" width="960" height="540">
  • Review: hero.jpg has no alt attribute.
  • Observed: divider.svg has empty alt text, which may be correct for decoration.
  • Observed: chart.webp supplies descriptive alt text and dimensions.
  • Not evaluated: actual transfer sizes, rendered dimensions, and the page's LCP element.
 
 
 
How to use it
  1. Enter the public URL containing the images you want to review.
  2. Choose Audit images and inspect each evidence-backed raw-HTML check.
  3. Separate missing alt attributes from intentionally empty decorative alt text.
  4. Use a rendered performance test for any item this report marks not evaluated.
 
 
 
       
     
     
What the results mean
A finding reflects only markup visible in the response. Missing attributes and clearly unsupported patterns require attention; observations such as empty alt text need human context. A pass confirms one implemented rule, while not evaluated explicitly means the tool did not request or render enough evidence.
 
How it works
The checker fetches the public page and parses its raw HTML into a document context. Image-category detectors inspect supported img attributes and ImageObject markup, then return structured severity, summary, and evidence fields. It does not request the image files themselves.
 
Features
  • Alt-attribute coverage and image-markup checks.
  • Loading hints, format clues, and supported ImageObject signals.
  • Evidence from the page source without uploading image assets.
  • Explicit not-evaluated output for render- and network-dependent checks.
 
Limitations
The tool cannot see CSS backgrounds, canvas content, JavaScript-injected images, visual image meaning, file bytes, compression quality, rendered display size, or real performance timing. It cannot write alt text responsibly without seeing and understanding the image in context.
 
Frequently asked questions
Should every image have descriptive alt text?
Every img element should have an alt attributeAlt text is the value of the `alt` attribute on an HTML `<img>` element — a short text substitute chosen for the image's purpose and context, not a literal description of what it shows. It makes images accessible to screen-reader users and helps search engines understand images, mainly for image search., but decorative images should usually use an empty alt value. Informative images need concise text that conveys their purpose in context.
Can this tool identify the Largest Contentful Paint image?
No. Actual LCPLargest Contentful Paint — render time of the largest visible image or text block, relative to when the page started loading. ≤2.5 s (at the 75th percentile) is good. requires a rendered performance measurement. This checker reports that check as not evaluated rather than guessing from source order or filename.
Does WebP automatically improve image SEO?
No. A modern format can reduce transfer size, but search visibility also depends on relevance, accessibilityWeb accessibility means designing sites so people with disabilities can use them, per the W3C's WCAG guidelines. It overlaps with SEO in specific, checkable ways — alt text, heading structure, descriptive link text, captions, and page speed all serve both audiences — but Google has said accessibility itself is not a ranking factor, and most WCAG success criteria (keyboard focus order, ARIA live regions, form labels) have no SEO effect at all., discoverability, surrounding text, and correct page implementation.
Why are CSS background images missing?
The checker reads image signals in raw HTML. It does not fetch stylesheets or render CSS, so background images and JavaScript-inserted images are outside its evidence set.
 
Next stepContent Gap Analyzer — look up the exact spec and expected values.

People also explore
ToolHeading Structure CheckerToolAccessibility TesterToolLink AnalyzerArticleAlt TextArticleThe HTML lang AttributeArticleRanking in Google Images
 
 
 
Feature requests for Image Seo Checker
 

Upvote what you want most. New ideas can be submitted from the floating Feedback menu;
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Where this tool helps
Common use cases
Audit image accessibility signals
Find missing or empty alt attributes in raw HTML and decide whether each image is informative or decorative.
Review loading hints
Inspect lazy-loading and fetch-priority attributes for obvious implementation gaps on important images.
Check source formats
Inventory image URLs and formats to find legacy or inconsistent delivery patterns worth reviewing.
Verify ImageObject markup
See whether raw HTML exposes relevant ImageObject structured data without assuming rendered or downstream eligibility.
Watch the full workflow
Image SEO Checker walkthrough
Read the transcript

      
      

        
Image SEO Checker

        

        
Images need useful markup, but a raw-H-T-M-L audit cannot responsibly guess visual meaning or performance. I’ll show you how to run the page check, separate missing from intentionally empty alt text, review dimensions, loading hints, formats, and ImageObject evidence, understand not-evaluated results, use Render Gap for rendered signals, and prioritize fixes with human context.

      

      

        
Step 1

        

        
Use this checker for accessibility review, template changes, image migrations, and prelaunch audits. It inspects supported image attributes and ImageObject markup in a public page’s raw H-T-M-L without downloading the image files or guessing what they depict.

      

      

        
Step 2

        

        
Enter the complete page U-R-L and choose Audit images. The server fetches bounded raw H-T-M-L, and browser-side detectors return structured findings with evidence. A truncated response is labeled so missing images and complete-document coverage are not assumed.

      

      

        
Step 3

        

        
Run it after changing a shared image component, migrating formats, adding structured data, or publishing a media-heavy page. Review each flagged element in its real context, because correct alternative text depends on the image’s purpose for that page.

      

      

        
Step 4

        

        
This walkthrough uses fictional example dot com markup and does not imply a live fetch. A real run selects Audit images and waits for the page response. The results always distinguish observed source evidence from checks requiring rendering or asset requests.

      

      

        
Step 5

        

        
Start with the final audited U-R-L and whether the result represents complete raw H-T-M-L or a partial captured prefix. If acquisition is truncated, absence and complete-document checks remain not evaluated rather than appearing as passes.

      

      

        
Step 6

        

        
An img element should have an alt attribute. Informative images need concise text conveying purpose in context; decorative images usually need alt equals empty. Missing and empty are different states. Confirm the intended role with the page author or designer.

      

      

        
Step 7

        

        
Source width and height attributes help reserve aspect ratio and reduce layout shift, but they do not reveal the final displayed dimensions. Check that declared values reflect the intrinsic asset ratio, then verify responsive rendering in the browser.

      

      

        
Step 8

        

        
Lazy loading is helpful for offscreen images but can delay an above-the-fold hero. Raw source order cannot reliably identify the real L-C-P element. Treat the hint as a review prompt, then measure the rendered page under realistic device and network conditions.

      

      

        
Step 9

        

        
Supported ImageObject markup can provide structured image evidence, but its presence does not guarantee enhanced search appearance. Validate the complete schema graph, ensure the U-R-Ls are crawlable, and keep markup consistent with visible page content.

      

      

        
Step 10

        

        
Actual transfer size, compression quality, rendered dimensions, and L-C-P require asset requests or a render budget. Visual meaning requires seeing the image in context. This tool says not evaluated instead of inventing evidence, and links to Render Gap for rendered signal comparison.

      

      

        
Step 11

        

        
The audit cannot see C-S-S background images, canvas content, JavaScript-injected images, file bytes, compression artifacts, visual meaning, display size, or real performance timing. A modern format alone does not make an image relevant, accessible, or discoverable.

      

      

        
Step 12

        

        
Trace repeated findings to the shared image component. Add intentional alt behavior, accurate intrinsic dimensions, and appropriate loading and fetch hints. Review every informative image visually, run Render Gap and a performance test, then confirm the deployed page’s accessibility and discoverability.

      

      

        
Fix source markup—measure rendered behavior separately.

        

        
Update the image component or content source with intentional alt behavior, accurate dimensions, and appropriate loading hints. Inspect the actual images in context, use a rendered performance test for L-C-P and display behavior, verify important assets remain discoverable and accessible, then rerun both source and rendered checks.

      

    
 
          
 
Common issues & how to fix them
 
     
  •  Warning Image lacks an alt attribute Fix: Add concise alt text that communicates each meaningful image’s purpose, and use empty alt attributes for decorative images. 
  •  Warning First image is lazy-loaded and may be LCP Fix: Confirm the actual LCP element first, then remove lazy loading from the above-the-fold LCP image if this image is responsible. 
  •  Information Likely-LCP image lacks high fetch priority Fix: Add fetchpriority=high only if performance testing confirms the first image is the above-the-fold LCP image. 
  •  Information Image uses a legacy source format Fix: Compare transfer size and quality, then serve an AVIF or WebP source with a compatible fallback when it materially reduces bytes. 
  •  Information ImageObject markup is absent Fix: Add ImageObject only for a primary image that benefits from structured description, and keep its URL and metadata accurate. 
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