Sitespeed

About Sitespeed

Sitespeed.io is an open source web performance testing tool that produces an HTML report including Core Web Vitals (Largest Contentful Paint, Interaction to Next Paint, Cumulative Layout Shift, First Contentful Paint, and TTFB), a video recording of page load, a HAR waterfall, and advice from a built-in "Coach" on how to fix performance issues. It can be run against a single page or a scripted user journey, and supports throttling network connectivity, running tests on real Android phones, and testing Safari on iOS. Results can be shipped to Graphite or InfluxDB for ongoing monitoring via Grafana dashboards, with a Docker Compose setup available to run the full monitoring stack.

The project is built around a family of related tools: Browsertime (the underlying browser timing/measurement engine), and standalone packages including the Coach, PageXray, Chrome-HAR, and Throttle, which can be used independently by developers building their own performance tooling. It can be installed via Docker (which bundles Firefox, Chrome, Edge, and XVFB) or via npm.

Sitespeed.io is aimed at developers and teams who need to debug slow pages or continuously monitor site performance over time. It is free to use, has been maintained since 2012, does not include tracking or analytics in its tools or dashboard, and does not send data back to the project maintainers.

Key features

• Generates HTML performance reports with Core Web Vitals, page-load video, and HAR waterfall
• Ships metrics to Graphite or InfluxDB for continuous monitoring via Grafana dashboards
• Runs via Docker (with Firefox, Chrome, Edge, XVFB pre-installed) or npm install
• Supports connection throttling, scripted user journeys, and testing on real Android and iOS Safari devices
• Coach feature provides advice on how to fix slow-loading pages

Frequently asked questions