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Use when reviewing image assets, markup, and CDN or build transforms related to Compress images without quality loss. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.
Use when reviewing templates, rendered HTML, or shared components related to Implement accessible breadcrumb navigation. Validate the final browser-facing markup, not just the source framework abstraction.
Use when auditing metadata, crawlability, structured data, or indexability related to Implement valid BreadcrumbList schema. Verify the rendered HTML and HTTP response rather than relying only on source files.
Use when reviewing templates, rendered HTML, or shared components related to Declare UTF-8 character encoding. Validate the final browser-facing markup, not just the source framework abstraction.
Use when reviewing templates, rendered HTML, or shared components related to Set text direction for RTL languages. Validate the final browser-facing markup, not just the source framework abstraction.
Use when auditing a site's meta tag uniqueness, generating page-specific meta descriptions, or reviewing CMS templates that inject the same description globally.
Use when you need to find the 2-3 most popular and well-maintained npm packages relevant to a frontend checklist rule, validate they meet quality thresholds, and add them to the rule's frontmatter.
| name | image-compression |
| description | Use when reviewing image assets, markup, and CDN or build transforms related to Compress images without quality loss. Check encoded size, rendered size, loading strategy, and above-the-fold impact together. |
| metadata | {"category":"images","priority":"high","difficulty":"beginner","estimatedTime":"15","source":"frontendchecklist.io","url":"https://frontendchecklist.io/en/rules/images/image-compression"} |
Uncompressed images are often 5-10x larger than needed—proper compression dramatically reduces page weight and load times with minimal visual impact.
Analyze if images are properly compressed without significant quality loss.
Compress images using tools like ImageOptim, TinyPNG, or automated build processes.
Explain how proper compression can reduce image sizes by 60-80% with minimal quality impact.
Review image assets, markup, and delivery configuration related to Compress images without quality loss. Flag exact files or components where format choice, sizing, or loading behavior violates the rule, and describe how to confirm the fix in DevTools.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/en/rules/images/image-compression
