> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/GoogleChrome/lighthouse/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Lighthouse analyzes web pages and apps, collecting modern performance metrics and surfacing actionable insights on developer best practices.

Lighthouse is an open-source, automated tool for improving the quality of web pages. It runs a series of audits against a URL and generates a report covering performance, accessibility, SEO, and best practices. Results are never sent to a remote server — all analysis happens locally using a Chrome instance on your machine.

## What Lighthouse measures

Lighthouse audits your page across four categories, each producing a score from 0–100.

<CardGroup cols={2}>
  <Card title="Performance" icon="gauge-high">
    Core Web Vitals (LCP, CLS, INP), Time to Interactive, Speed Index, and more — simulated on a mid-tier mobile device over a 4G connection.
  </Card>

  <Card title="Accessibility" icon="universal-access">
    Automated checks powered by axe-core, covering ARIA usage, color contrast, keyboard navigation, and semantic markup.
  </Card>

  <Card title="SEO" icon="magnifying-glass">
    Crawlability, meta tags, structured data, mobile friendliness, and other ranking-relevant signals.
  </Card>

  <Card title="Best Practices" icon="shield-check">
    HTTPS enforcement, modern JavaScript APIs, secure headers, browser compatibility, and more.
  </Card>
</CardGroup>

## Three ways to run Lighthouse

<CardGroup cols={2}>
  <Card title="Chrome DevTools" icon="chrome" href="https://developer.chrome.com/docs/devtools/">
    Open the **Lighthouse** panel in Chrome DevTools and click **Generate report**. No installation required.
  </Card>

  <Card title="CLI quickstart" icon="terminal" href="/quickstart-cli">
    Install the `lighthouse` package globally and audit any URL from your terminal. Best for automation and scripting.
  </Card>

  <Card title="Node.js quickstart" icon="node-js" href="/quickstart-node">
    Import Lighthouse as a Node module and integrate audits directly into your scripts or tooling.
  </Card>

  <Card title="Lighthouse CI" icon="circle-play" href="https://github.com/GoogleChrome/lighthouse-ci">
    Run Lighthouse on every commit, track score changes over time, and block regressions in CI.
  </Card>
</CardGroup>

## Requirements

Lighthouse requires **Node.js 22 (LTS) or later**. Check your version with:

```bash theme={null}
node --version
```

## Next steps

<CardGroup cols={2}>
  <Card title="CLI quickstart" icon="terminal" href="/quickstart-cli">
    Install and run your first audit in under a minute
  </Card>

  <Card title="Node.js quickstart" icon="node-js" href="/quickstart-node">
    Use Lighthouse programmatically in your Node.js scripts
  </Card>
</CardGroup>