How to Use PortPreview with an Express.js App

To use PortPreview with an Express.js app, listen on 0.0.0.0 (or app.listen(PORT) without binding to localhost only), run npx portpreview PORT, and register the HTTPS URL for webhooks, OAuth callbacks, and API demos.

Why tunnel Express

Express remains the default HTTP layer for Node APIs and BFFs. Payment providers, CRM webhooks, and OAuth servers need a public HTTPS endpoint while you debug middleware order and raw-body parsing locally.

• Webhooks. Mount express.raw() on webhook paths before express.json(). Details in Express webhook local testing.
• OAuth. Set redirect URIs to your tunnel origin. See OAuth callback testing.
• Sharing APIs. Let mobile or frontend teams hit your local API without VPN. See share local dev server.

Quick start

1. Start Express: node server.js or npm run dev on port 3000.
2. Run npx portpreview 3000.
3. Test GET https://your-tunnel.portpreview.dev/health.
4. Configure provider webhooks to POST https://your-tunnel.portpreview.dev/api/webhooks/....

Minimal Express server

import express from 'express';

const app = express();
const PORT = process.env.PORT ?? 3000;

app.get('/health', (_req, res) => res.json({ ok: true }));

app.listen(PORT, () => {
  console.log(`Listening on http://localhost:${PORT}`);
});

Express listens on all interfaces by default. If you bind explicitly, use '0.0.0.0' so the tunnel process can forward traffic.

Trust proxy headers

Behind PortPreview your app sees X-Forwarded-Proto: https. Enable trust proxy when generating absolute URLs or secure cookies:

app.set('trust proxy', 1);

CORS for split frontends

If a React or Vue dev server on another port calls your Express API through separate tunnels, configure CORS explicitly:

import cors from 'cors';
app.use(cors({ origin: process.env.FRONTEND_TUNNEL_URL }));

Security checklist

• Verify webhook signatures before parsing JSON.
• Never expose unauthenticated admin routes on a shared tunnel.
• Stop the tunnel when finished. See tunnel security.

Express documentation covers middleware and routing. Start PortPreview free.