🖼️ Free Image SEO Analyzer

Image Alt Text Checker
& Image SEO Analyzer

Check any webpage for missing alt text, image format issues, missing dimensions, lazy loading gaps, and other image SEO problems that hurt your rankings.

Fetching page and analyzing images…

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What Does This Image SEO Analyzer Check?

Good image SEO goes beyond just adding alt text. This tool checks every image on your page for the full set of signals Google uses to understand and rank your visual content.

🏷️ Alt Text (Most Critical)

Alt text tells Google what an image shows. Missing alt text means Google skips the image entirely. Keyword-stuffed alt text can trigger spam penalties. We check for missing, empty, too-short, and too-long alt attributes on every image.

📐 Width & Height Attributes

Images without explicit width and height cause Cumulative Layout Shift (CLS) — a Core Web Vitals metric Google uses as a ranking signal. We flag every image missing its dimensions.

⚡ Lazy Loading

The loading="lazy" attribute defers off-screen images, improving page load speed. We check which images have it and which don't (above-the-fold images should load eagerly).

🎨 Image Format

WebP images are 25–35% smaller than JPEG/PNG with equal quality, directly improving LCP (Largest Contentful Paint). We flag non-WebP images as optimization opportunities.

🔗 Image URLs

We detect external images (third-party CDN or hotlinked), relative vs absolute paths, and images without a src attribute — all of which can cause SEO or performance issues.

Frequently Asked Questions

Why does image alt text matter for SEO? ▼
Alt text (alternative text) is the HTML attribute that describes an image to search engines and screen readers. Google cannot visually interpret images — it relies on alt text to understand what an image shows and how it relates to the page content. Missing or empty alt text means Google indexes your images with no context, reducing your chances of appearing in Google Image Search and weakening the topical relevance signals on your page. Well-written alt text that naturally includes target keywords improves both accessibility and image SEO.
What is the ideal length for image alt text? ▼
The ideal alt text length is 5 to 15 words (roughly 50–125 characters). It should be descriptive and specific — describing what the image actually shows while naturally incorporating a relevant keyword if appropriate. Avoid keyword stuffing — Google penalizes this. For decorative images that don't add content meaning, use an empty alt attribute (alt="") so screen readers skip them.
What is lazy loading and does it affect SEO? ▼
Lazy loading (loading="lazy") defers the loading of off-screen images until the user scrolls near them. This improves page speed and Core Web Vitals — both Google ranking signals. However, images above the fold should NOT use lazy loading — they should load instantly. Only images below the fold should be lazy-loaded. Googlebot supports lazy loading but may not scroll to trigger deferred images, so critical images should always be eagerly loaded.
Should I use WebP format for SEO? ▼
Yes. WebP images are 25–35% smaller than equivalent JPEG/PNG files with the same visual quality. Smaller images load faster, directly improving Core Web Vitals (particularly Largest Contentful Paint) and overall page speed — both Google ranking factors. All modern browsers support WebP. If your images are still serving as .jpg or .png, converting to WebP is a quick technical win.
Why should images have explicit width and height attributes? ▼
When images don't have explicit width and height attributes in the HTML, the browser doesn't know how much space to reserve for them before they load. This causes Cumulative Layout Shift (CLS) — the page jumps around as images load, which frustrates users and is penalized by Google's Core Web Vitals scoring. Adding width and height attributes reserves space upfront and eliminates layout shift. This is a direct Core Web Vitals optimization.
What images should have empty alt text vs descriptive alt text? ▼
Decorative images — icons, dividers, backgrounds, purely visual spacers — should have empty alt text (alt="") because they don't add informational content. Informational images — product photos, screenshots, charts, diagrams, team photos, infographics — should have descriptive alt text. Functional images (like a logo that links to the homepage) should have alt text describing their function, not just appearance (e.g., "AutoSEOBot homepage" not "blue robot logo").