How to Build a Node.js/Express REST API in 5 Minutes with AI

Why This Matters

Most developers still spin up new Express servers by copy-pasting boilerplate or running express-generator, but more than 80% now use some form of AI coding tool weekly - and they expect instant solutions that work out of the box and get them up and running in minutes.

With the steps below you will have a working REST API in under five minutes, combining a minimal Express.js core with an AI agent to generate the repetitive parts.

Prerequisites

• Node.js ≥ 20 installed (check with node -v)
• pnpm or npm for packages
• An AI coding agent (e.g. Line0, Cursor)

Step 1 - Set up the project (1 min)

mkdir todo-api && cd todo-api
pnpm init -y
pnpm add express
pnpm add -D @types/express @types/node ts-node tsup typescript

express is a lightweight web framework that makes routing and middleware straightforward.

Step 2 - Generate your first route with AI (1 min)

Open your AI tool and paste a prompt such as:

"Create a minimal Express REST API with routes for GET /status and POST /echo. Return JSON responses."

The agent will generate a file similar to this:

// src/server.ts
import express from "express";

const PORT = process.env.PORT || 3000;

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

// A quick endpoint example
app.get('/status', (_req, res) => res.json({ ok: true }));
app.post('/echo', (req, res) => res.json(req.body));

app.listen(PORT, () =>
  console.log(`API listening on port ${PORT}`));

Under the hood this is identical to the canonical “hello-world” Express example.

Step 3 - Add your first endpoints (1 min)

Type the following prompt in your AI coding tool:

"Add a /tasks resource with full CRUD endpoints using Express Router; include in-memory storage."

The coding agent should now generate a new router file src/routes/tasks.ts with .get, .post, .put, and .delete handlers and placeholders for all your business logic.

The src/server.ts file should also be updated with the new /task router.

Step 4 - Update package.json run scripts (1 min)

To bundle the project's TS files we can use tsup which offers a lightweight way to bundle your packages and run your service.

Add the following scripts to package.json:

 "scripts": {
    "dev:local": "tsup --watch --onSuccess 'npm run local:serve'",
    "local:serve": "pkill -f 'node dist/server.js'; node dist/server.js &",
  }

Here dev:local bundles the project files and runs in --watch mode which handles hot reloading. On each change we need to restart the service so we run local:serve to kill the process and start it again. This is a simpler and cleaner implementation instead of configuring nodemon for your TS express.js apps.

Step 5 - Run & test (1 min)

You can use tools like Postman or curl to test your new endpoints:

pnpm run dev:local    # start the server
curl http://localhost:3000/status

You should see { "ok": true } as a response.

Optional: One prompt generation

You can use a tool like Line0 which is an AI pair programmer and handles the full project setup, basic boilerplate, package.json configuration and implements the logic end to end with 0 coding required.

Use a simple prompt like:

"Build a TODO api service with CRUD endpoints for tasks as well as a /status health check endpoint."

It will set up everything for you in a few seconds and give you a fully working service you can build on.

You can then ask it for more complex business logic, database integrations, implementation of 3rd party APIs and so on.

FAQ

Q: How safe is AI-generated code?
A: Treat it like any other template-review logic, add validation, and write tests. The GitHub CEO recently noted that true productivity comes from switching fluidly between AI output and manual edits, not blind copy-paste.

Q: What if I only have two minutes?
Use Line0's backend pair programmer to get up and running in seconds.