How to use Site Speed Test Tool
- Paste or load a Lighthouse JSON report (or paste it) into Site Speed Test Tool.
- Hit Read report and Site Speed Test Tool computes the result client-side.
- Use the category scores and Core Web Vitals Site Speed Test Tool produces — nothing was uploaded.
About this tool
Site Speed Test Tool runs entirely in your browser. Export a report from Chrome DevTools or PageSpeed Insights and load the JSON into Site Speed Test Tool 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 Tool for?
Site Speed Test Tool runs entirely on your device: add your input, and it checks it locally in real time.
Is Site Speed Test Tool free to use?
Yes — Site Speed Test Tool is completely free, with no usage limits.
Does Site Speed Test Tool upload my data?
No — Site Speed Test Tool processes everything locally in your browser, so nothing you enter is uploaded or stored.
What file does Site Speed Test Tool read?
Export a Lighthouse or PageSpeed Insights JSON report and load it into Site Speed Test Tool; it surfaces the scores and Core Web Vitals locally.
Does Site Speed Test Tool work offline?
Once the page has loaded, Site Speed Test Tool keeps working with no network connection.