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Building a Lighthouse Performance Monitor: Tracking Web Performance Over Time

The Challenge: Measuring Performance Impact of Major Changes

When our team decided to overhaul both our website's frontend interface and Content Management System (CMS), we faced a critical question: How would we measure the performance impact of these changes?

Google's Lighthouse is an excellent tool for performance auditing. You run it, get your scores, and see what needs improvement. But here's the problem: Lighthouse gives you a snapshot, not a story.

When you're planning major changes like a complete CMS migration or frontend redesign, you need more than point-in-time measurements. You need:

That's why I built the Lighthouse Performance Monitor - an automated tool that transforms Lighthouse from a one-time audit tool into a continuous monitoring solution.

The Solution: Automated Daily Monitoring with Visual Trends

The Lighthouse Performance Monitor is a lightweight automation wrapper around Google's Lighthouse that:

  1. Runs daily automated audits using cron jobs
  2. Stores historical data in JSON and CSV formats
  3. Generates visual trend charts showing performance over time
  4. Tracks all key metrics: Performance, Accessibility, SEO, and Best Practices

Real-World Benefits for Product Managers and Developers

For Product Managers:

For Frontend Developers:

A Practical Use Case: The CMS Migration Journey

Let me share a practical scenario that mirrors the motivation behind this tool:

Week 1-4 (Baseline Period)

Week 5-8 (Migration Phase)

Week 9-12 (Post-Launch)

Months 3-6 (Long-term)

Without automated monitoring, these insights would be invisible. You'd only have "before" and "after" snapshots, missing the entire journey and valuable optimization opportunities.

How It Works: Simple Architecture, Powerful Results

The tool uses a hybrid approach combining Node.js and Python:

Daily Cron Job Triggers
        ↓
Node.js runs Lighthouse audit
        ↓
Saves JSON report with timestamp
        ↓
Node.js aggregates all reports into CSV
        ↓
Python generates visual trend charts
        ↓
2x2 grid visualization ready

Key Features:

🤖 Fully Automated

📊 Visual Insights

💾 Data Portability

⚙️ Highly Configurable

Getting Started in 5 Minutes

The tool is designed for minimal setup friction:

# 1. Clone the repository
git clone https://github.com/c3nk/lighthouse-performance-monitor.git
cd lighthouse-performance-monitor

# 2. Install dependencies
pip install -r requirements.txt
npm install

# 3. Configure your website URL
# Edit Lighthouse Report Script.js and update the domain variable

# 4. Run it!
./run-all.sh

That's it! You'll get your first report and trend chart immediately.

To automate it daily:

# Add to crontab (runs daily at 6 AM)
0 6 * * * /path/to/lighthouse-performance-monitor/run-all.sh >> /path/to/lighthouse.log 2>&1

Why This Approach Works

Leveraging Industry Standards

Rather than building a performance monitoring tool from scratch, this project leverages Google's battle-tested Lighthouse engine. You get:

Minimal Overhead, Maximum Value

The tool's philosophy is "do one thing well": automate Lighthouse and visualize trends. It doesn't try to be a full APM (Application Performance Monitoring) solution. Instead, it:

Design Process Integration

This isn't just a monitoring tool it's a design process tool. By running it throughout your redesign or migration project, you:

What Could Come Next

While the current version focuses on core functionality, there's room for enhancement:

These features aren't implemented yet, but the foundation is ready for community contributions.

The Hidden Benefit: Seasonal Pattern Recognition

One of the most valuable and unexpected insights from long-term monitoring is seasonal pattern recognition.

In the short term (days or weeks), you can't distinguish between:

But with months of data, patterns emerge:

These insights are impossible to obtain from one-time audits or even weekly manual checks.

Conclusion: From Snapshots to Stories

Google Lighthouse is powerful, but it's designed for point-in-time analysis. For teams planning major changes - redesigns, migrations, platform upgrades - you need continuous monitoring.

The Lighthouse Performance Monitor transforms Lighthouse from a diagnostic tool into a strategic performance intelligence system. It helps you:

Whether you're a Product Manager justifying a redesign investment or a Frontend Developer optimizing for Core Web Vitals, having historical performance data changes everything.

Get Started Today

The project is open source and available on GitHub: https://github.com/c3nk/lighthouse-performance-monitor

License: MIT (free to use, modify, and distribute)

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