Font Loading Performance Checker

Analyze web font request waterfalls, transfer sizes, formats, and layout shift risks.

Target Website URL

Inspects web fonts, @font-face declarations, formats (WOFF2/WOFF/TTF), font-display, preloads, and real network durations.

Key Capabilities

7 capabilities

#	Capability
01	Audits all page font requests, file sizes, and transfer durations
02	Detects WOFF2, WOFF, TTF, OTF, and variable web font formats
03	Inspects font-display descriptors (swap, optional, block, fallback)
04	Verifies preload link tags (<link rel='preload' as='font'>)
05	Highlights slow font downloads and Cumulative Layout Shift (CLS) risks
06	Distinguishes self-hosted vs third-party font CDNs (Google Fonts, Adobe)
07	One-click CSV export of all font resource network timings

How to Use the Font Loading Performance Checker

Step 01

Enter Website URL

Provide the target URL and select desktop or mobile viewport.

Step 02

Analyze Font Waterfall

The server audits network requests, CSS @font-face rules, and caching headers.

Step 03

Optimize Web Fonts

Review actionable suggestions like font-display: swap, WOFF2 conversions, and preloading.

Frequently Asked Questions

How do web fonts affect Core Web Vitals?

Slow web fonts delay First Contentful Paint (FCP) and trigger Cumulative Layout Shift (CLS) when unstyled system fonts swap with custom fonts (FOUT/FOIT).

Why is WOFF2 recommended over TTF or OTF?

WOFF2 uses Brotli compression, delivering font files that are typically 30% to 50% smaller than standard TTF or OTF files with identical glyph quality.

Should all web fonts be preloaded?

No. Preload only 1 to 2 critical fonts required for above-the-fold content to avoid bandwidth contention with critical CSS and scripts.

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