# Lighthouse Lighthouse is an open-source automated tool by Google for auditing web page quality. It runs audits across five categories: Performance, Accessibility, Best Practices, SEO, and Progressive Web App (PWA) compliance. Each category produces a score from 0 to 100. ## How to use - **Chrome DevTools**: Audits panel (built-in, no install needed) - **Chrome extension**: Lighthouse browser extension - **CLI**: `npm install -g lighthouse` then `lighthouse https://example.com` - **Node module**: programmatic usage via `const lighthouse = require('lighthouse')` - **PageSpeed Insights**: https://pagespeed.web.dev (runs Lighthouse under the hood with real-world CrUX data) ## CLI usage ```bash # Basic audit lighthouse https://example.com # Output as JSON lighthouse https://example.com --output json --output-path report.json # Specific categories only lighthouse https://example.com --only-categories=performance,accessibility # Run in headless mode (CI-friendly) lighthouse https://example.com --chrome-flags="--headless" ``` ## Key metrics (Performance) - First Contentful Paint (FCP) - Largest Contentful Paint (LCP) - Total Blocking Time (TBT) - Cumulative Layout Shift (CLS) - Speed Index ## References - https://github.com/GoogleChrome/lighthouse - https://developer.chrome.com/docs/lighthouse ## Related - [[Search Engine Optimization (SEO)]] - [[Accessibility (a11y)]] - [[Core Web Vitals]]