Building HTTP Servers: raw http → Express → Fastify

After this lesson, you will be able to: Build HTTP servers: raw http module → Express → Fastify.

Each layer adds productivity. Knowing all three makes you fluent across legacy + modern codebases.

Prerequisites:npm Ecosystem

Raw http (no framework)

Useful for low-level tasks; rarely used directly.

python

import { createServer } from "node:http";

const server = createServer((req, res) => {
  res.writeHead(200, { "Content-Type": "application/json" });
  res.end(JSON.stringify({ url: req.url, method: req.method }));
});

server.listen(3000, () => console.log("on :3000"));

Express (the workhorse)

Still the default. Mature; huge ecosystem.

python

import express from "express";
import { z } from "zod";

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

app.get("/users", async (req, res) => {
  const users = await db.user.findMany();
  res.json(users);
});

const CreateUser = z.object({ name: z.string(), email: z.string().email() });
app.post("/users", async (req, res) => {
  const parsed = CreateUser.safeParse(req.body);
  if (!parsed.success) return res.status(400).json({ error: parsed.error.flatten() });
  const user = await db.user.create({ data: parsed.data });
  res.status(201).json(user);
});

app.listen(3000);

Fastify (faster + typed)

Built-in schema validation. Worth choosing for new projects.

python

import Fastify from "fastify";
import { z } from "zod";

const app = Fastify({ logger: true });

app.get("/users", async () => db.user.findMany());

const CreateUser = z.object({ name: z.string(), email: z.string().email() });
app.post("/users", async (req, reply) => {
  const parsed = CreateUser.safeParse(req.body);
  if (!parsed.success) {
    reply.code(400);
    return { error: parsed.error.flatten() };
  }
  const user = await db.user.create({ data: parsed.data });
  reply.code(201);
  return user;
});

await app.listen({ port: 3000 });

When to use which

Raw http: rare; for protocols below HTTP or extremely minimal services. Express: legacy default. Pick when joining an Express team. Fastify: new project default. Faster, schema-validated by design, better TS story. Hono: edge runtime + ultrafast; production-credible for Vercel / Cloudflare / Bun.

Quick Check

Why pick Fastify over Express for a new API?

Pick the senior answer.

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