Optimizing the User Experience: A Guide to Improving Your Website's Speed and Responsiveness
Measure Core Web Vitals of any URL directly from the browser. No external APIs – use Browser Performance API & iframes with sandbox attribute.
Come utilizzare Live Site Performance
Insert URL to analyze
Attach full site address (with http:// or https://) and choose device class, Desktop or Mobile.
Start Analysis
The tool loads the URL into a hidden iframe sandbox and reads real-time data via Browser Performance API for up to about 15 seconds.
Metric Units and Recommendations
Check overall verdict, values of LCP/INP/CLS/FID/TTFB vs Good/Better/Limited and priority recommendations.
Suggerimenti
- Repeat the measurement a couple of times: since it's an in-browser sampling, values can vary between runs.
- Headset works on both desktop and mobile devices: many sites have different CWV between the two device classes.
- If you see "Estimated (locked iframe)", consider the values as indicative and verify with a dedicated laboratory tool.
Domande frequenti
How are Core Web Vitals measured?
The tool loads the target URL into a hidden iframe sandbox and reads PerformanceNavigationTiming directly in the browser: no external APIs, no remote servers involved.
What happens if the site blocks iframes?
If the site prevents embedding via header SAMEORIGIN or CSP frame-ancestors, metrics are estimated from loadTime and navigator.connection, and the result is labeled as estimate.
Are measurements equivalent to Lighthouse or PageSpeed Insights?
Edge cases (Good/Improvable/Limited) are aligned with Lighthouse, but measurement occurs in your browser on a single load, not in a controlled lab environment: values may vary compared to a dedicated Lighthouse audit.
Why choose Desktop or Mobile affects the result?
Class of device affects evaluation thresholds and context of recommendations: Mobile is generally more severe because it reflects slower connections and CPUs.
Are my browsing data sent to a server?
No. The entire measurement is client-side: the URL is loaded only in your browser via an iframe sandbox and no data is sent to external servers.