Lighthouse Audit

Automate Google Lighthouse audits to measure and track Core Web Vitals, SEO, and accessibility - the same metrics Google uses for search ranking.

When to Use This Skill

• Performance optimization - Measure LCP, FID, CLS before and after changes

• SEO audits - Check technical SEO issues (meta tags, structured data, etc.)

• Accessibility checks - Identify a11y issues for compliance

• Client reporting - Generate professional performance reports

• Monitoring - Track scores over time across multiple pages

What Claude Does vs What You Decide

Claude Does You Decide

Structures analysis frameworks Metric definitions

Identifies patterns in data Business interpretation

Creates visualization templates Dashboard design

Suggests optimization areas Action priorities

Calculates statistical measures Decision thresholds

Dependencies

pip install click pandas jinja2

Also requires Chrome and Lighthouse CLI

npm install -g lighthouse

Or use Chrome DevTools built-in Lighthouse

Commands

Single URL Audit

python scripts/main.py audit https://example.com --categories performance,seo python scripts/main.py audit https://example.com --format html --output report.html

Batch Audit

python scripts/main.py batch urls.txt --output results/ python scripts/main.py batch urls.txt --categories performance --format csv

Compare Before/After

python scripts/main.py compare https://example.com --baseline scores.json python scripts/main.py compare https://example.com --baseline-url https://staging.example.com

Monitor Over Time

python scripts/main.py history https://example.com --days 30 python scripts/main.py history https://example.com --plot

Examples

Example 1: Full Site Performance Audit

Create URL list

cat > urls.txt << EOF https://example.com/ https://example.com/pricing https://example.com/features https://example.com/blog EOF

Run batch audit

python scripts/main.py batch urls.txt --categories performance,seo,accessibility

Output: results/audit_2024-01-15/

├── example.com_.json

├── example.com_pricing.json

├── example.com_features.json

├── example.com_blog.json

└── summary.csv

Example 2: Before/After Comparison

Save baseline

python scripts/main.py audit https://example.com --output baseline.json

Make optimizations...

Compare

python scripts/main.py compare https://example.com --baseline baseline.json

Output:

Core Web Vitals Comparison

─────────────────────────────

Metric Before After Change

LCP 3.2s 1.8s -44% ✓

FID 120ms 45ms -63% ✓

CLS 0.25 0.08 -68% ✓

Performance 52 89 +37 pts

Example 3: Generate Client Report

Full audit with HTML report

python scripts/main.py audit https://client-site.com
--format html
--output client-report.html
--include-screenshots

Output: Professional HTML report with:

- Executive summary

- Core Web Vitals scores

- Screenshots of issues

- Prioritized recommendations

Audit Categories

Category Checks Impact

performance

LCP, FID, CLS, TTFB, Speed Index Search ranking

seo

Meta tags, headings, links, mobile Search visibility

accessibility

WCAG compliance, contrast, labels Compliance

best-practices

HTTPS, security, modern APIs Trust

pwa

Service worker, manifest, offline App-like experience

Core Web Vitals Thresholds

Metric Good Needs Improvement Poor

LCP (Largest Contentful Paint) ≤2.5s 2.5s-4.0s

4.0s

FID (First Input Delay) ≤100ms 100ms-300ms

300ms

CLS (Cumulative Layout Shift) ≤0.1 0.1-0.25

0.25

INP (Interaction to Next Paint) ≤200ms 200ms-500ms

500ms

Output Formats

Format Use Case Content

json

Automation, storage Full raw data

csv

Spreadsheets, analysis Summary scores

html

Client reports Visual report

md

Documentation Markdown summary

Skill Boundaries

What This Skill Does Well

• Structuring data analysis

• Identifying patterns and trends

• Creating visualization frameworks

• Calculating statistical measures

What This Skill Cannot Do

• Access your actual data

• Replace statistical expertise

• Make business decisions

• Guarantee prediction accuracy

Related Skills

• schema-markup - Fix structured data issues

• image-batch - Optimize images for LCP

• link-checker - Find broken links

Skill Metadata

• Mode: centaur

category: seo-tools subcategory: performance dependencies: [lighthouse, click, pandas] difficulty: beginner time_saved: 3+ hours/week