How we built InterceptAPI: Real-time traffic diagnosis

The Problem

When developing modern web applications, diagnosing API requests often involves opening the browser's DevTools Network tab. But what happens when you need to inspect webhook payloads from a third-party service like Stripe, or share a locally hosted API with a client across the globe?

We needed a tool that could act as a local tunnel while providing deep, real-time inspection of incoming requests.

The Solution

We built InterceptAPI, a platform that combines local tunneling with an intuitive diagnostic dashboard.

Core Technologies

• Next.js: For the sleek dashboard and frontend application.
• Node.js & WebSockets: To instantly stream incoming payload data to the active dashboard.
• Local Tunneling (ngrok alternative): Custom proxy tunneling using standard TCP relays.

WebSockets in Action

To ensure that the user sees requests the moment they hit the server, we implemented a robust WebSocket architecture.

// Example WebSocket broadcaster
io.on('connection', (socket) => {
  console.log('Client connected for real-time logs');
  
  // Broadcast incoming HTTP requests
  requestEmitter.on('new_request', (data) => {
    socket.emit('log_stream', data);
  });
});

By leveraging Socket.io, we bypassed the latency of traditional HTTP polling entirely. The moment a Stripe Webhook hits the InterceptAPI proxy, it's instantly painted on the user's dashboard.

Conclusion

Building InterceptAPI was an incredible challenge in optimizing real-time data streams and building a developer-friendly UX. Check it out at interceptapi.in.