API Latency Monitor 🚀

A lightweight and production-ready Express middleware for monitoring API latency, response times, slow endpoints, and backend performance in Node.js applications.

✨ Features

• ⚡ Real-time API latency tracking
• 🚨 Automatic slow API detection
• 🎨 Colored terminal logs
• 📊 Status code monitoring
• 🪶 Lightweight middleware
• 🔧 Configurable slow API threshold
• 📈 Backend performance visibility
• 🛠 Easy Express integration
• 🚀 Zero-config setup

❓ Why API Latency Monitor?

Debugging slow APIs in production is difficult.

Traditional logging systems are often:

• reactive instead of proactive
• difficult to analyze
• missing latency visibility
• hard to monitor in real time

api-latency-monitor solves this by providing:

• instant API response tracking
• real-time slow endpoint detection
• lightweight monitoring
• clean terminal visibility
• minimal setup

📦 Installation

npm install api-latency-monitor

🚀 Quick Start

Basic Usage

const express = require("express");
const monitor = require("api-latency-monitor");

const app = express();

app.use(
  monitor({
    slowThreshold: 1000
  })
);

app.get("/", (req, res) => {

  setTimeout(() => {
    res.send("Fast API");
  }, 300);

});

app.get("/slow", (req, res) => {

  setTimeout(() => {
    res.send("Slow API");
  }, 2000);

});

app.listen(3000, () => {
  console.log("🚀 Server running on port 3000");
});

🖥 Example Output

Fast API

[GET] / -> 200 -> 302ms

Slow API

⚠️ SLOW API [GET] /slow -> 200 -> 2010ms

⚙️ Configuration

| Option | Type | Default | Description | |---|---|---|---| | slowThreshold | number | 1000 | Time in milliseconds after which API is considered slow |

📚 API

monitor(options)

Parameters

{
  slowThreshold: number
}

Returns

Express middleware function.

🏗 How It Works

The middleware:

1. Captures request start time
2. Waits for response completion
3. Calculates total response time
4. Logs latency information
5. Detects slow endpoints automatically

📂 Real-World Use Cases

• Detect slow database queries
• Monitor backend performance
• Analyze API bottlenecks
• Debug latency spikes
• Monitor payment APIs
• Improve Express application performance
• Track slow endpoints during development

🛠 Production Ready

Designed for:

• Express.js applications
• Node.js APIs
• internal services
• microservices
• staging environments
• production deployments

Lightweight architecture ensures minimal runtime overhead.

📈 Future Roadmap

• [ ] Average response time tracking
• [ ] Request analytics dashboard
• [ ] Error monitoring
• [ ] File logging support
• [ ] Live terminal dashboard
• [ ] WebSocket monitoring
• [ ] Grafana integration
• [ ] Request history tracking
• [ ] Memory usage analytics

📊 Example Monitoring Scenario

Suppose your application has multiple APIs:

/users
/login
/products
/orders
/payments

The middleware automatically tracks latency for every endpoint and highlights slow APIs instantly.

Example:

[GET] /users -> 200 -> 120ms

[POST] /login -> 200 -> 95ms

⚠️ SLOW API [GET] /payments -> 200 -> 2200ms

💡 Why Use This Package?

If you want:

• quick API visibility
• lightweight monitoring
• instant latency tracking
• backend debugging
• slow API detection

without using expensive monitoring tools, this package provides a simple and effective solution.

🤝 Contributing

Contributions are welcome!

Feel free to:

• open issues
• suggest new features
• submit pull requests

📄 License

MIT © Harsh Rana

👨‍💻 Author

Harsh Rana

• GitHub: https://github.com/HarshRana446
• LinkedIn: https://www.linkedin.com/in/harsh-rana-739878302

⭐ Support

If you found this package useful, consider starring the GitHub repository 🚀