Lighthouse

Lighthouse

Audit performance, accessibility, SEO and best practices for websites.

Setup

1. Check if installed:

   command -v node && node --version
   command -v npx && npx lighthouse --version 2>/dev/null || npm list -g lighthouse 2>/dev/null
   

2. Install:

   # Node.js (required for npx / lighthouse)
   # macOS
   brew install node
   
   # Ubuntu / Debian
   sudo apt update && sudo apt install -y nodejs npm
   
   # Lighthouse (use npx, no install needed)
   npx lighthouse <url> --output=json --chrome-flags="--headless --no-sandbox"
   
   # Or install globally
   npm install -g lighthouse
   

Run Audit

# Full audit (output to terminal)
npx lighthouse <url> --output=json --chrome-flags="--headless --no-sandbox" 2>/dev/null | jq '{
  performance: .categories.performance.score,
  accessibility: .categories.accessibility.score,
  bestPractices: .categories["best-practices"].score,
  seo: .categories.seo.score
}'

# Save HTML report
npx lighthouse <url> --output=html --output-path=./lighthouse-report.html --chrome-flags="--headless --no-sandbox"

# Performance only
npx lighthouse <url> --only-categories=performance --output=json --chrome-flags="--headless --no-sandbox"

Categories

Interpret Scores

• 90-100: Good (green)
• 50-89: Needs Improvement (orange)
• 0-49: Poor (red)

Key Metrics (Core Web Vitals)

Compare Results

# Run multiple times and compare
for i in 1 2 3; do
  npx lighthouse <url> --output=json --chrome-flags="--headless --no-sandbox" 2>/dev/null | \
    jq -r '"Run '$i': perf=\(.categories.performance.score) a11y=\(.categories.accessibility.score)"'
done

Tips

• Run 3+ times and average (results vary)
• Use --chrome-flags="--headless --no-sandbox" for servers
• Scores are multiplied by 100 (0.95 = 95 points)
• Use --preset=desktop to simulate desktop (default is mobile)
• Install Chrome/Chromium on server if not available

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