Complete Bun Tutorial: From Zero to Deployment

This complete beginner-to-production blog will help you understand Bun, build an app with it, compare it with Node.js, and deploy it to production.

🚀 What is Bun?

Bun is a modern JavaScript runtime designed as a fast, all-in-one replacement for:

Node.js runtime
npm / yarn / pnpm
Jest / Vitest
Webpack / Vite (for many use cases)

Why Bun?

⚡ Extremely fast (written in Zig)
📦 Built-in package manager
🧪 Built-in test runner
🔥 Native TypeScript support
🧵 Web-standard APIs (fetch, WebSocket)

🧠 When Should You Use Bun?

Use Case	Bun Fit
Backend APIs	✅ Excellent
Microservices	✅ Very good
CLI tools	✅ Fast
Large legacy Node apps	⚠️ Gradual migration
Heavy native addons	❌ Node still better

🛠️ Step 1: Install Bun

Windows (PowerShell)

powershell -c "irm bun.sh/install.ps1 | iex"

macOS / Linux

curl -fsSL https://bun.sh/install | bash

Verify installation:

bun --version

📁 Step 2: Create a Bun Project

bun init

Choose:

Project name
Entry file (index.ts recommended)
TypeScript: Yes

Project structure:

my-bun-app/
├── index.ts
├── bun.lockb
├── package.json
└── tsconfig.json

🧩 Step 3: Create a Simple Bun Server

`index.ts`

const server = Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello from Bun 🚀");
  },
});

console.log(`Server running on http://localhost:${server.port}`);

Run:

bun run index.ts

🌐 Step 4: REST API Example

Bun.serve({
  port: 3000,
  fetch(req) {
    const url = new URL(req.url);

    if (url.pathname === "/api/health") {
      return Response.json({ status: "OK", runtime: "bun" });
    }

    return new Response("Not Found", { status: 404 });
  },
});

📦 Step 5: Install Packages (Bun vs npm)

bun add express

✔ Faster than npm
✔ Creates bun.lockb
✔ No node_modules overhead

🧪 Step 6: Testing with Bun

import { test, expect } from "bun:test";

test("basic math", () => {
  expect(2 + 2).toBe(4);
});

Run tests:

bun test

⚡ Bun vs Node.js (Detailed Comparison)

Feature	Bun	Node.js
Runtime speed	⭐⭐⭐⭐⭐	⭐⭐⭐
Startup time	Ultra fast	Slower
TypeScript	Native	Needs ts-node
Package manager	Built-in	npm / yarn
Testing	Built-in	Jest / Vitest
Web APIs	Native	Partial
Ecosystem	Growing	Massive
Stability	New	Mature

Performance Snapshot

Bun HTTP server ≈ 2–4x faster
Cold start ≈ 10x faster
Dependency install ≈ 5–20x faster

👉 Node.js wins for legacy, enterprise & native addons
👉 Bun wins for speed, DX & modern apps

🔁 Migrating from Node.js to Bun

Most Node apps work without changes.

Replace:

node index.js

With:

bun index.ts

Supported:

Express
Fastify
Prisma
Sequelize
React / Vite backends

🚀 Deployment Tutorial (Production)

✅ Option 1: Deploy Bun on VPS (Ubuntu)

Install Bun on Server

curl -fsSL https://bun.sh/install | bash

Run App

bun run index.ts

🔁 Option 2: Run with PM2 (Recommended)

npm install -g pm2
pm2 start "bun run index.ts" --name bun-app
pm2 save

🐳 Option 3: Docker Deployment

`Dockerfile`

FROM oven/bun:latest

WORKDIR /app
COPY . .
RUN bun install

EXPOSE 3000
CMD ["bun", "run", "index.ts"]

Build & run:

docker build -t bun-app .
docker run -p 3000:3000 bun-app

☁️ Option 4: Cloud Deployment

Platform	Bun Support
VPS (AWS / DigitalOcean)	✅ Best
Railway	✅
Fly.io	✅
Vercel	⚠️ Limited
Render	⚠️ Experimental

🔐 Production Best Practices

Use .env with Bun.env
Enable logging
Add health checks
Use reverse proxy (NGINX)
Monitor memory & CPU

📌 Final Thoughts

Bun is not just faster Node.js — it’s a new-generation runtime.

If you’re:

Building new products
Creating APIs / microservices
Want best developer experience

👉 Choose Bun

SeeB4Coding