How to use Fast Web Speed Test
- Give Fast Web Speed Test a Lighthouse JSON report (or paste it) to work from.
- Click Read report — Fast Web Speed Test processes everything on your device.
- Review the category scores and Core Web Vitals shown below.
About this tool
Fast Web Speed Test runs entirely in your browser. Fast Web Speed Test reads a Lighthouse or PageSpeed Insights JSON report in your browser and surfaces the headline numbers without a server.
Because Fast Web Speed Test parses a report you provide, the results match whatever run you exported. Nothing you enter is uploaded, and it keeps working offline once the page has loaded.
Frequently asked questions
How do I use Fast Web Speed Test?
Fast Web Speed Test lets you check your input right in the browser, with the result shown instantly and nothing uploaded.
Is Fast Web Speed Test free to use?
Yes — Fast Web Speed Test is completely free, with no usage limits.
Does Fast Web Speed Test upload my data?
No — Fast Web Speed Test processes everything locally in your browser, so nothing you enter is uploaded or stored.
What file does Fast Web Speed Test read?
Export a Lighthouse or PageSpeed Insights JSON report and load it into Fast Web Speed Test; it surfaces the scores and Core Web Vitals locally.
Does Fast Web Speed Test work on mobile?
Yes — Fast Web Speed Test is just a web page and runs on any modern browser, including phones and tablets.