Early Hints (HTTP 103)

Early Hints sends Link: rel=preload HTTP headers before the main HTML response. Supported browsers can start fetching critical resources earlier, which improves perceived loading speed and Core Web Vitals.

Where to configure

1. Open ZiziCache → Optimization.
2. Go to the Early Hints (103) section.
3. Enable Early Hints and select the resource types to preload.

Enable Early Hints (103)

Sends 103 Early Hints headers to supported browsers for critical resources.

Resource types

• Preload CSS stylesheets — Includes CSS files in Early Hints preloading.
• Preload JavaScript files — Includes JavaScript files in Early Hints preloading.
• Preload font files — Includes font files in Early Hints preloading.
• Preload image files — Includes critical images in Early Hints preloading.

Early Hints uses the plugin’s preload URL lists (for example, font and CSS preload URLs). If no preload URLs are configured, no Early Hint headers are sent for that type.

Crossorigin support

Enable crossorigin support adds the crossorigin attribute for CORS resources (fonts, stylesheets from CDN).

Fetch Priority

Controls browser resource prioritization for preloaded assets:

• Auto — Browser decides.
• High — Prioritize critical resources.
• Low — Defer loading of non-critical resources.

Debug mode

Enable debug mode adds debug headers to inspect Early Hints behavior (development only).

Requirements & compatibility

• Early Hints works with Cloudflare (available on the free plan) or other supported integrations.
• Alternative: hosting must support HTTP 103 or HTTP/2 Server Push (rare).
• Browser support: Chrome 103+, Edge 103+, Opera 89+.
• Server requirement: HTTP/2 or HTTP/3 is recommended for best results.

Benefits

• Faster page loads by starting resource fetches earlier.
• Reduced render-blocking for CSS and JavaScript.
• Better LCP when fonts and images are preloaded.
• Improved TTFB perception as the browser works while the server renders.

Notes

• Early Hints are HTTP headers, not HTML tags. They won’t appear in the page source.
• Use debug mode only for troubleshooting and disable it afterwards.