| name | webfont-format |
| description | Use when reviewing stylesheets, component styles, and responsive behavior related to Optimize web font formats. Check the rendered layout across breakpoints and interaction states before proposing a fix. |
| metadata | {"category":"css","priority":"medium","difficulty":"intermediate","estimatedTime":"20","source":"frontendchecklist.io","url":"https://frontendchecklist.io/en/rules/css/webfont-format"} |
Optimize web font formats
Modern font formats reduce file sizes by 30-50%—directly improving page load speed and Core Web Vitals scores.
Quick Reference
- Use WOFF2 as primary format (~30% smaller than WOFF)
- Include WOFF fallback for older browsers
- Apply font-display: swap for better perceived performance
- Preload critical fonts and subset to reduce file sizes
Check
Verify that web fonts use modern formats (WOFF2, WOFF) with proper fallbacks and are optimized for performance with font-display and preloading strategies.
Fix
Convert fonts to WOFF2/WOFF formats, implement proper font loading strategies, and optimize font delivery with compression and caching.
Explain
Explain how modern web font formats reduce file sizes, improve loading performance, and provide better browser support compared to legacy formats.
Code Review
Review stylesheets, component styles, and responsive states related to Optimize web font formats. Flag exact selectors, declarations, or breakpoints that violate the rule in the rendered UI.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/en/rules/css/webfont-format
