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name: image-cdn description: "Use when reviewing image assets, markup, and CDN or build transforms related to Serve images from a CDN. Check encoded size, rendered size, loading strategy, and above-the-fold impact together." metadata: category: images priority: high difficulty: intermediate estimatedTime: "30" source: frontendchecklist.io url: https://frontendchecklist.io/rules/images/image-cdn

Serve images from a CDN

Image CDNs automatically optimize, resize, and convert images on-the-fly—delivering the smallest file in the best format without manual processing.

Quick Reference

• Use image CDN for automatic format conversion (WebP, AVIF)
• Generate responsive sizes on-the-fly via URL parameters
• CDN edge caching delivers images from nearest location
• Popular options: Cloudinary, Imgix, Cloudflare Images, Vercel

Check

Verify if images are served from a CDN or image optimization service.

Fix

Configure an image CDN like Cloudinary, Imgix, or Cloudflare Images for automatic optimization.

Explain

Explain how image CDNs provide on-the-fly optimization, resizing, and format conversion.

Code Review

Review image assets, markup, and delivery configuration related to Serve images from a CDN. Flag exact files or components where format choice, sizing, or loading behavior violates the rule, and describe how to confirm the fix in DevTools.

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For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/images/image-cdn