What’s the difference between lab and field data?

Lab data (Lighthouse) runs in a controlled environment to surface opportunities; field data (CrUX) reflects real users across devices and networks.

Do I need an API key?

No. The tool proxies requests through a secure server route so your API key isn’t exposed.

How often is CrUX updated?

CrUX trends represent weekly snapshots over roughly the last 25 weeks, giving a clear picture of changes over time.

Google Web Vitals Report

Measure Core Web Vitals using PageSpeed Insights and CrUX History. Get Lighthouse score, field data, and trends for a great user experience.

Website URL

Performance Best Practices

Serve next‑gen images (AVIF/WebP) and preconnect to critical origins.
Use font-display: swap and preload key fonts to avoid FOIT/FOUT.
Inline critical CSS and defer non‑critical scripts.

Break up long tasks; leverage requestIdleCallback for non‑urgent work.
Prefer CSS transforms for animations; avoid layout thrashing.
Measure continuously—monitor LCP, INP, CLS after every release.

Lighthouse Performance

Synthetic lab score with metrics like FCP, TBT, SI, LCP, and CLS.

Field Data (CrUX)

Real-user p75 for LCP, INP, and CLS with weekly historical series.

Trends & History

Spot regressions and improvements with concise sparkline trends.

What are Google Core Web Vitals?

Core Web Vitals are user‑centric performance metrics that capture loading, interactivity, and visual stability. This tool combines PageSpeed Insights (lab data) and the Chrome UX Report (field data) to help you diagnose and improve real‑world experience.

How to use

Enter a full URL (https://) and run the report.
Review CrUX history for LCP, INP, and CLS to spot regressions.
Check Lighthouse details to identify render‑blocking, images, and scripts to optimize.

Best practices

Optimize LCP by serving properly sized, compressed hero images and enabling HTTP/2/3.
Reduce INP by minimizing long tasks, deferring non‑critical JS, and using interaction‑ready states.
Prevent CLS with fixed dimensions for images/ads and avoid late‑loading fonts without fallback.

FAQs

What’s the difference between lab and field data?: Lab data (Lighthouse) runs in a controlled environment to surface opportunities; field data (CrUX) reflects real users across devices and networks.
Do I need an API key?: No. The tool proxies requests through a secure server route so your API key isn’t exposed.
How often is CrUX updated?: CrUX trends represent weekly snapshots over roughly the last 25 weeks, giving a clear picture of changes over time.

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