PageSpeed Insights
Lab and field performance data for a single URL
PageSpeed Insights reports how a page performs, combining a Lighthouse lab test run on demand with field data from the Chrome User Experience Report where enough real visits exist. The distinction matters: lab numbers are reproducible and useful for debugging, while field data reflects what actual visitors experienced on their own devices and connections.
The report lists Core Web Vitals, diagnostics such as render-blocking resources or oversized images, and estimated savings for each fix. It is free, needs no account, and works on any public URL, including a competitor's. For sites with little traffic, field data may be unavailable, in which case the lab results and the diagnostics are still a reasonable place to start.