How to use Site Speed Test
- Add a Lighthouse JSON report (or paste it) to Site Speed Test to get started.
- Press Read report to run it locally in your browser.
- Review the category scores and Core Web Vitals shown below.
About this tool
Everything Site Speed Test does happens on your own device. Export a report from Chrome DevTools or PageSpeed Insights and load the JSON into Site Speed Test to see the scores locally.
It shows category scores and Core Web Vitals such as LCP, CLS and TBT, read straight from the JSON. No data is sent anywhere, so it stays fast and private by default.
Frequently asked questions
What is Site Speed Test for?
Site Speed Test lets you check your input right in the browser, with the result shown instantly and nothing uploaded.
Do I need an account for Site Speed Test?
No — Site Speed Test needs no account, sign-up or installation.
Does Site Speed Test upload my data?
No — Site Speed Test processes everything locally in your browser, so nothing you enter is uploaded or stored.
What file does Site Speed Test read?
Export a Lighthouse or PageSpeed Insights JSON report and load it into Site Speed Test; it surfaces the scores and Core Web Vitals locally.
Can I use Site Speed Test without a connection?
Yes — after the first load Site Speed Test runs entirely offline.