Express Server Typed with TypeScript

Install dependencies

npm i express
npm i -D @types/express

Basic typed server

import express, { Request, Response } from 'express';

const app = express();
app.use(express.json());

app.get('/ping', (req: Request, res: Response) => {
  res.json({ message: 'pong' });
});

app.post('/users', (req: Request<{ }, {}, { name: string }>, res: Response) => {
  const { name } = req.body;
  res.status(201).json({ id: Date.now(), name });
});

app.listen(4000, () => console.log('🚀 4000'));

Error‑handling middleware typed

import { NextFunction } from 'express';

function errorHandler(err: any, _req: Request, res: Response, _next: NextFunction) {
  console.error(err);
  res.status(500).json({ error: err.message ?? 'Internal Server Error' });
}
app.use(errorHandler);