How to deploy a Node.js Express app for free

Your Express server runs on localhost:3000. To put it online you need three small changes: the port, the start script, and where secrets live. This guide covers all three, plus MongoDB.

Step 1: Listen on the right port

server.js

const express = require('express');
const app = express();

app.use(express.json());

app.get('/', (req, res) => res.send('API is running'));
app.get('/health', (req, res) => res.json({ status: 'ok' }));

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => console.log(`Listening on ${PORT}`));

Hosting platforms assign the port through the PORT variable. Hard-coding app.listen(5000) is the number one reason Express deploys fail their health check.

Step 2: Fix package.json

package.json

{
  "name": "my-api",
  "version": "1.0.0",
  "main": "server.js",
  "scripts": {
    "start": "node server.js",
    "dev": "nodemon server.js",
    "test": "node --test"
  },
  "engines": { "node": ">=20" },
  "dependencies": {
    "express": "^4.21.0",
    "mongoose": "^8.7.0"
  },
  "devDependencies": {
    "nodemon": "^3.1.0"
  }
}

• start uses node, not nodemon. Nodemon is for development, where it restarts on file changes.
• Commit package-lock.json so the server installs exactly the versions you tested.
• Every require() must be listed in dependencies. A package installed globally on your laptop doesn't exist on the server.
• Add node_modules/ and .env to .gitignore.

Step 3: Connect MongoDB the right way

mongodb://localhost:27017 only works on your laptop. Create a free cluster on MongoDB Atlas and read the URL from an environment variable:

const mongoose = require('mongoose');

mongoose.connect(process.env.MONGODB_URI)
  .then(() => console.log('MongoDB connected'))
  .catch((err) => { console.error(err); process.exit(1); });

• In Atlas, under Network Access, allow your host's IP address (or 0.0.0.0/0 for testing). Otherwise the connection times out.
• In Shipzo, add MONGODB_URI=mongodb+srv://... under your project's Settings → Environment variables. Values are masked in every log.

Step 4 (optional): Add a test

Node has a built-in test runner. With a test script in place, Shipzo runs it before every deploy and blocks the release if it fails:

test/app.test.js

const test = require('node:test');
const assert = require('node:assert');

test('adds numbers', () => {
  assert.strictEqual(1 + 1, 2);
});

Step 5: Push and deploy

git add .
git commit -m "Production ready"
git push

1. Create a free Shipzo account → New deployment.
2. Paste the repo link, add your environment variables in step 5 of the form, and press Deploy.

Shipzo detects Express from package.json, installs with npm ci, runs npm test, builds a Node 20 container, starts it with npm start, waits for GET / to answer, then switches traffic. Your API is live at https://your-api.shipzo.tech.

Common errors and fixes

Frequently asked questions