Deno vs Bun vs Node.js: The Ultimate Runtime Showdown

Introduction: The JavaScript Runtime Evolution

The JavaScript runtime landscape has exploded with competition:

• Node.js (2009): The established veteran
• Deno (2018): Secure TypeScript-first runtime
• Bun (2022): All-in-one speed demon

This 4,000+ word technical guide compares them across 6 critical dimensions with:

• Reproducible benchmarks (HTTP servers, file ops, DB queries)
• Architecture diagrams
• Real-world migration examples
• Decision frameworks for different use cases

1. Architectural Breakdown

Node.js: The CommonJS Legacy

Key Characteristics:

• CommonJS modules (require())
• Callback-first non-blocking I/O
• Massive npm registry (1.5M+ packages)

Deno: Secure TypeScript Runtime

Key Innovations:

• Built-in TypeScript compiler
• Secure-by-default (file/network permissions)
• Web-standard APIs (fetch, WebSocket)

Bun: The All-in-One Runtime

Breakthrough Features:

• JavaScriptCore engine (Safari's engine)
• Native-speed SQLite integration
• Drop-in Node.js compatibility

2. Performance Benchmarks

Test Environment

• M1 Max (32GB RAM)
• Runtime versions:
  • Node.js 20.11
  • Deno 1.40
  • Bun 1.0.22

HTTP Server Throughput

// Node.js
const http = require('http');
http.createServer((req, res) => res.end('Hello')).listen(3000);

// Deno
Deno.serve({ port: 3000 }, () => new Response('Hello'));

// Bun
Bun.serve({ port: 3000, fetch: () => new Response('Hello') });

Results (Requests/sec):

Key Insight: Bun's runtime architecture (JavaScriptCore + Zig-native HTTP server) outperforms Node's (V8 + libuv) in HTTP throughput benchmarks.

Filesystem Operations

// Reading 10,000 files
// Node.js
const fs = require('fs/promises');
await Promise.all(files.map(f => fs.readFile(f)));

// Deno
await Promise.all(files.map(f => Deno.readTextFile(f)));

// Bun
await Promise.all(files.map(f => Bun.file(f).text()));

Results (ms):

3. Feature Comparison

TypeScript Support

Deno Example:

// Runs directly
deno run app.ts

Package Management

# Node.js
npm install lodash

# Deno 
import lodash from "npm:lodash";

# Bun
bun add lodash  # 28x faster than npm

Installation Speed (sec):

Web Compatibility

// All runtimes support:
fetch('https://api.example.com')
  .then(res => res.json())

API Coverage:

4. Security Models

Permission Systems

Node.js:

# Full system access by default
node script.js

Deno:

# Explicit permissions
deno run --allow-net app.ts

Bun:

# Node.js-compatible with gradual security
bun run --untrusted-code-mitigations script.js

Security Scorecard:

5. Real-World Use Cases

API Server Development

Node.js:

// Express.js example
const app = require('express')();
app.get('/', (req, res) => res.json({ status: 'ok' }));
app.listen(3000);

Deno:

// Oak framework
import { Application } from "oak";
const app = new Application();
app.use(ctx => ctx.response.body = { status: 'ok' });
await app.listen({ port: 3000 });

Bun:

// Elysia.js
import { Elysia } from 'elysia';
new Elysia().get('/', () => ({ status: 'ok' })).listen(3000);

Framework Ecosystem:

6. Migration Guide

Node.js → Deno

1. Change require() to ES imports
2. Add file extensions (.js → .ts)
3. Set permissions in deno.json

Example:

- const fs = require('fs');
+ import { readFile } from 'node:fs/promises';

Node.js → Bun

1. Replace npm with bun commands
2. Optional: Use Bun's native APIs
3. Test edge cases (Node.js core module differences)

Example:

# Before
npm start

# After
bun run start

Decision Framework

Choose Node.js When:

• You need maximum ecosystem compatibility
• Enterprise stability is critical
• Using legacy CommonJS modules

Choose Deno When:

• Security is top priority
• Building TypeScript-first applications
• Want browser-compatible APIs

Choose Bun When:

• Performance is the primary concern
• Need an all-in-one toolkit (test runner, bundler)
• Developing new projects without legacy constraints

Selection Algorithm:

Benchmark Setup Instructions

1. Install Runtimes

# Node.js
nvm install 20

# Deno
curl -fsSL https://deno.land/x/install/install.sh | sh

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

2. Run HTTP Tests

# Node.js
node server.js

# Deno
deno run --allow-net deno-server.ts

# Bun
bun run bun-server.js

3. Execute Benchmarks

# Using autocannon
autocannon -c 100 -d 30 http://localhost:3000

The Verdict

While Node.js remains the safest choice for enterprise applications:

• Bun is 3x faster for new projects
• Deno provides superior security for sensitive applications
• Node.js has the deepest ecosystem for complex integrations

Final Recommendation:

Use Bun for greenfield projects, Deno for security-first apps, and Node.js for legacy systems.

Which runtime are you using? Share your benchmarks below! 🚀