Image SEO Checklist: Automated SEO Workflow

Overview

Images account for the largest portion of page weight on most websites. Properly optimized images improve page speed, earn traffic from Google Images, and enhance accessibility. This checklist covers every aspect of image SEO from file optimization to markup.

File Optimization

• Convert all images to modern formats (WebP or AVIF) with JPEG/PNG fallbacks where needed
• Compress images to the smallest file size that maintains acceptable visual quality (80-85% quality for photos)
• Resize images to the maximum display size — never serve a 3000px image that displays at 600px
• Implement responsive images with srcset and sizes attributes for different viewport widths
• Remove unnecessary EXIF metadata from images to reduce file size
• Use SVG format for logos, icons, and illustrations (not raster formats)

File Naming

• Name image files descriptively using keywords: blue-running-shoes-nike.webp not IMG_4521.webp
• Use hyphens to separate words in file names
• Keep file names lowercase
• Avoid special characters and spaces in file names
• Include relevant product or content keywords in the file name

Alt Text

• Add alt text to every meaningful image on the site
• Write descriptive alt text that explains what the image shows (not just keyword stuffing)
• Include the target keyword naturally when the image is relevant to that keyword
• Keep alt text under 125 characters
• Use empty alt attributes (alt="") for purely decorative images
• Do not start alt text with “image of” or “picture of” — screen readers already announce it as an image

HTML Markup

• Set explicit width and height attributes on all img elements to prevent layout shift
• Add loading=“lazy” to images below the fold
• Do not lazy load images above the fold (especially the LCP image)
• Add fetchpriority=“high” to the LCP image to prioritize its loading
• Use the picture element for art direction across different viewport sizes
• Implement decoding=“async” on non-critical images

Technical Delivery

• Serve images from a CDN for faster delivery across geographic regions
• Set appropriate cache headers (long cache duration for versioned image URLs)
• Enable HTTP/2 or HTTP/3 to allow parallel image loading
• Verify images are not blocked by robots.txt
• Check that image URLs are stable and do not change unnecessarily (breaking cached versions)

Structured Data

• Implement image sitemap tags for important images you want indexed in Google Images
• Include image URLs in Product schema for e-commerce product images
• Add image properties to Article schema for blog post featured images

Content and Placement

• Place the most important image near the top of the page content
• Use images that support and enhance the surrounding text content
• Include captions on images where they add context (captions are read 300% more than body text)
• Avoid text embedded in images — use HTML/CSS text overlays instead for SEO and accessibility

Monitoring

• Run Auditite’s image optimization audit monthly to catch unoptimized new images
• Track Google Images traffic in Google Search Console as a separate performance segment
• Monitor page weight trends to ensure new image uploads do not regress your performance gains
• Check for broken image URLs across the site using crawl data