言語

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 attribute, 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 LCP 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, accessibility, 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;
      requests appear here once approved, and the most-wanted rise to the top.

   
Loading…
  
  ➕ Request a feature   
New requests are reviewed before they appear here.
 
     
  
  
 
 
 
 
   
      
ツールについて
raw HTMLの画像シグナルを監査し、alt属性、遅延読み込み、fetch priority、画像形式、ImageObjectマークアップを確認します。
公開ページを取得して画像ごとの属性と構造化データを一覧にし、表示と配信に関する確認事項を分けて表示します。
機能
  • alt属性と代替テキストの確認
  • 遅延読み込みとLCP候補の確認
  • fetch priorityと画像形式の確認
  • ImageObject構造化データの検出
仕組み
raw HTMLからimg、picture、source、関連する属性とImageObject JSON-LDを抽出します。alt、loading、fetchpriority、形式、寸法、LCP候補を正規化し、欠落や旧形式を画像単位で分類します。
制限事項
  • 解析は取得したraw HTMLに限られ、ブラウザーの実際のLCP、画像の見た目、SNSキャッシュ、CDN挙動を保証しません。JavaScriptで後から追加される画像は含まれない場合があります。
  • 検出事項は確認の手掛かりであり、画像のデザイン品質、コンテンツとの関連、検索順位を判定しません。
よくある質問
画像をダウンロードして確認しますか？
主にHTMLの画像属性と構造化データを確認します。画像の表示品質や最終配信サイズは別途検証してください。
lazy loadingは常に問題ですか？
いいえ。画面外画像には有効です。最初の表示でLCPになる画像に使われているかを確認して判断してください。
ImageObjectがあれば画像SEOは保証されますか？
いいえ。構造化データは説明の補助です。URL、可視コンテンツ、ポリシー、実際の表示を別途確認してください。