Image SEO Analyzer – Audit Every Image

How to Use the Analyzer

1. Choose an input — fetch a URL, paste the page's HTML, or paste a plain list of image URLs.
2. Click "Analyze Images" — every image is checked and summarized in a table with per-image status.
3. Fix critical issues first — missing alt text is both an SEO and an accessibility failure.
4. Export the CSV if you are auditing many pages and want to track fixes in a spreadsheet.

What This Tool Checks

• Alt text — missing, empty, overly long, or alt that merely repeats the filename.
• Filenames — auto-generated names (IMG_1234), spaces, mixed case, and data-URI sources.
• Dimensions — missing width/height attributes that cause layout shift (CLS).
• Lazy loading — invalid loading values and below-the-fold images that load eagerly.
• Responsive images — missing srcset for bandwidth-optimized delivery.
• Formats — legacy JPG/PNG/GIF flagged with a suggestion to move to WebP/AVIF.
• Captions — figure/figcaption usage detected and reported.
• og:image — the social share image tag presence and value.

Why Image SEO Matters

Images are a search surface of their own: Google Image Search sends billions of clicks a month, and properly optimized images rank there. Images also feed page speed — Core Web Vitals, especially LCP and CLS, are heavily influenced by how images are sized, formatted and loaded. A page with lazy-loaded heroes, missing dimensions and 2MB PNGs will lose rankings to an identical page that serves compressed WebP with declared sizes. None of these fixes require a developer: they are attribute changes.

Image SEO Best Practices

• Write alt text that describes the image — "SEO tools comparison chart showing 2026 market leaders" beats "image 5".
• Name files before you upload — keyword-relevant, hyphenated, lowercase slugs.
• Declare width and height (or CSS aspect-ratio) to prevent layout shift.
• Serve WebP/AVIF with JPG/PNG fallbacks via <picture> for older browsers.
• Lazy-load below the fold, eager-load the hero.
• Add a 1200×630 og:image so shared links look professional.

Example: A Typical Image Audit

A blog post had 8 images. The analyzer found 2 missing alt attributes (both screenshots), 1 empty alt on a hero, 3 images without width/height, 2 PNG screenshots (legacy format), and 1 filename called "IMG_0451.jpg". The fixes were quick: describe the screenshots, add width/height to match rendering size, convert the PNGs to WebP, and rename the file to "seo-dashboard-screenshot.webp". The page's LCP improved by ~40% after the format swap.

Common Mistakes & How to Avoid Them

• Keyword-stuffing alt text. Google penalizes manipulative alt; write for humans describing the image.
• Lazy-loading everything. The hero should be eager — lazy heroes hurt LCP.
• Ignoring CLS. Missing dimensions is the #1 cause of layout shift on content pages.
• Skipping the og:image. A missing share image makes your content look unprofessional when shared.

Frequently Asked Questions

Can the analyzer check image file sizes?

Only when the browser can download the image (same-origin or CORS-enabled). The attribute-based checks above always work, and file size is best checked with DevTools.

Is alt text still relevant for ranking?

Yes — Google uses alt text to understand image content, and it remains a documented accessibility requirement. Write it for people first.

What is the recommended image size for the web?

Resize images to their rendered size (never upload 4000px photos for a 600px slot) and compress aggressively — under 200KB is a good target for most content images.

Related SEO Tools

Combine the audit with the Schema Markup Validator (image URLs inside JSON-LD fail validation all the time), the On-Page SEO Analyzer for the rest of the page, and the Content Optimization Analyzer to keep copy and images working together.