Express Status Monitor Plus is a lightweight, production-ready Application Performance Monitoring (APM) tool. It provides a beautiful, modern dashboard to track your server's health in real-time.

As an independent, heavily upgraded fork of the original express-status-monitor, this Plus version introduces critical enterprise features like persistent metrics across restarts, P50/P95/P99 percentiles, dark mode, and upstream health checks—all without the steep cost of commercial APMs like Datadog or New Relic.

✨ Why choose "Plus"? (Key Features)

• 💾 Persistent Storage: Metrics survive process restarts and deployments via a highly optimized, file-based ring buffer.
• 📊 Advanced Percentiles: Built-in reservoir sampling for P50, P95, and P99 response time tracking to catch edge-case latency.
• 🏥 Service Health Checks: Monitor the uptime of your upstream services and third-party APIs directly from the dashboard.
• 🎨 Modernized UI: Glassmorphism headers, dark/light/system themes, interactive charts with smooth animations.
• ⚡ Ultra-Lightweight: Just one single middleware and a ~200 KB bundled frontend. Zero massive dependencies.
• 📈 Comprehensive Metrics: Tracks CPU, memory, heap, load average, event loop latency, response times, requests/sec, and HTTP status codes.

📦 Installation

npm install express-status-monitor-plus

Requires Node.js ≥ 18

🚀 Quick Start

Add the monitor as the very first middleware in your Express application, before any other routes or middleware.

const express = require('express');
const statusMonitor = require('express-status-monitor-plus');

const app = express();

// Initialize the dashboard and data collection
app.use(statusMonitor());

app.get('/', (req, res) => res.send('Hello World'));

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
  console.log('Dashboard available at http://localhost:3000/status');
});

Navigate to http://localhost:3000/status to view your live metrics!

⚙️ Advanced Configuration

Pass a configuration object to tailor the dashboard exactly to your infrastructure needs.

app.use(statusMonitor({
  title: 'Express Status Monitor Plus',       // Dashboard page title
  path: '/status',                   // Dashboard URL path
  socketPath: '/socket.io',          // Socket.io endpoint path
  darkMode: 'auto',                  // 'auto' | 'dark' | 'light'
  
  // Storage & Persistence
  dataDir: '/var/data/my-app/metrics', // Custom metrics directory
  flushInterval: 30,                   // Seconds between disk writes
  
  // Data retention rules (interval in seconds, retention in data points)
  spans: { interval: 5,  retention: 60 },  // 1 point/5sec, keep for 5 min

  // Exclude specific routes from tracking
  ignoreStartsWith: '/admin',

  // Toggle specific charts
  chartVisibility: {
    cpu: true,
    mem: true,
    load: true,
    heap: true,
    eventLoop: true,
    responseTime: true,
    rps: true,
    statusCodes: true,
  },
}));

🏥 Upstream Health Checks

Keep an eye on the databases, microservices, or external APIs your Express app relies on. Endpoints returning a 200 OK are marked as healthy, while timeouts or other status codes trigger a failure alert on your dashboard.

app.use(statusMonitor({
  healthChecks: [
    {
      protocol: 'http',
      host: 'localhost',
      path: '/api/internal/health',
      port: '3000',
    },
    {
      protocol: 'https',
      host: 'api.stripe.com',
      path: '/v1/ping',
      port: '443',
    },
  ],
}));

🔒 Securing the Dashboard in Production

You should absolutely protect your /status route in production. The middleware exposes a pageRoute handler that easily wraps around your existing authentication strategies.

Example using http-auth (Basic Auth):

const auth = require('http-auth');
const basic = auth.basic({ realm: 'Monitor Area' }, (user, pass, callback) => {
  callback(user === 'admin' && pass === 'supersecret');
});

const statusMonitor = require('express-status-monitor-plus')({ path: '' });

app.use(statusMonitor.middleware);
app.get('/status', basic.check(statusMonitor.pageRoute));

🔌 Custom Socket.io Instances

If your application already leverages WebSockets, pass your existing Socket.io instance to prevent port conflicts and reuse your existing upgrade handlers.

const http = require('http');
const { Server } = require('socket.io');
const express = require('express');

const app = express();
const server = http.createServer(app);
const io = new Server(server);

app.use(require('express-status-monitor-plus')({
  websocket: io,
  port: 3000,
}));

🛠 Development

# Install dependencies
npm install

# Build assets (Rollup: JS + CSS + HTML → dist/)
npm run build

# Start dev server with live reload
npm run dev

# Watch mode (rebuild on file changes)
npm run build:watch

# Run tests
npm test

# Lint
npm run lint

📄 License

MIT