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Welcome to the wonderful world of web performance!

Using you can:

  • Test your web site against Web Performance best practices using the Coach.
  • Collect Navigation Timing API, User Timing API and Visual Metrics from Firefox/Chrome using Browsertime.
  • Run your custom-made JavaScript and collect whichever metric(s) you need.
  • Test one or multiple pages, across one or many runs to get more-accurate metrics.
  • Create HTML-result pages or store the metrics in Graphite.
  • Write your own plugins that can do whatever tests you want/need.

See all the latest changes in the Changelog.

If you use Firefox 55 (or later) please have a look at When 57 is released we think there will be a easy way to fix it :)

Examples of what you can do

Checkout our example

A summary report in HTML:

Individual page report:

Collected metrics from a URL in Graphite/Grafana:

Video - easiest using Docker. This gif is optimized, the quality is much better IRL:

Lets try it out

Using Docker (requires 1.10+):

$ docker run --shm-size=1g --rm -v "$(pwd)":/ sitespeedio/ --video --speedIndex

Or install using npm:

$ npm i -g

Or clone the repo and test the latest changes:

$ git clone
$ npm install
$ bin/sitespeed.js --help
$ bin/sitespeed.js

I want to help!

We have a special page for you!


All the love in the world to our contributors: