Node.js - Deploying Your TypeScript + Fastify App to Render.com

Project setup

Suppose you have a Node.js + TypeScript app like this:

my-app/

├── src/

│   └── index.ts

├── dist/

├── package.json

└── tsconfig.json

In package.json:

"scripts": {

  "build": "tsc",

  "start": "node dist/index.js"

}

tsconfig.json:

{

  "compilerOptions": {

    "target": "ES2022",

    "module": "ES2022",

    "moduleResolution": "node",

    "strict": true,

    "esModuleInterop": true,

    "skipLibCheck": true,

    "rootDir": "src",  

    "outDir": "dist",

  },

  "include": ["src"]

}

Your tsconfig.json compiles src/ into dist/.

Render.com settings summary

Build Command:

npm install && npm run build

Start Command:

npm start

Problem: No open ports detected

After deploying, Render might show:

==> No open ports detected on 0.0.0.0, continuing to scan..

This usually happens because Fastify’s default listen() binds to localhost (127.0.0.1).

Render’s routing layer can’t access your server on that address.

 Fix: bind Fastify to 0.0.0.0

In your src/index.ts (or wherever you start Fastify):

import fastify from 'fastify';

const app = fastify();

const port = process.env.PORT ? parseInt(process.env.PORT) : 3000;

app.get('/', async () => {

  return { message: 'Hello from Fastify!' };

});

app.listen({ port: port, host: '0.0.0.0' }, (err, address) => {

  if (err) throw err;

  console.log(`🚀 Backend running at ${address}`);

});