Bun vs Node.js vs Deno: The JavaScript Runtime Battle in 2025

Hello HaWkers, the JavaScript ecosystem has never been as interesting as it is now. In 2025, we have three runtimes competing for developers attention, and the most surprising news of the year was Bun acquisition by Anthropic.

Have you ever wondered which runtime to use for your next project? Node.js is the reliable veteran, Deno promised to revolutionize security, and Bun arrived with absurd speed. Lets analyze each one in depth.

The Current State of Runtimes in 2025

Current Versions

• Bun 1.3: Released in October 2025, with acquisition by Anthropic
• Deno 2.5: Bringing V8 14.0 and TypeScript 5.9.2
• Node.js 24: Preparing for LTS designation in October

Adoption Numbers

Monthly downloads (npm/registries):

• Node.js: Billions (industry standard)
• Bun: 7+ million monthly
• Deno: 2+ million monthly

💡 News: Bun acquisition by Anthropic signals that the "batteries-included" approach has backing from a leading AI company.

Performance Comparison

Startup Time

In tests for simple HTTP server initialization:

Runtime	Startup Time
Bun 1.3	~8ms
Deno 2.5	~35ms
Node.js 24	~42ms

Bun is 5x faster than Node.js to start!

HTTP Throughput

Requests per second on "Hello World" server:

Runtime	Requests/second
Bun 1.3	~120,000 req/s
Deno 2.5	~85,000 req/s
Node.js 24	~32,000 req/s

Bun processes 3-4x more requests than Node.js.

Package Installation

Installing 100 packages from a medium project:

Runtime	Time
Bun	~2s
pnpm	~8s
npm	~15s
yarn	~12s

Bun 1.3: The New Performance Leader

What Makes Bun Special

Bun was written from scratch in Zig, a low-level language, focusing on maximum performance:

// server.js - Simple HTTP server in Bun
const server = Bun.serve({
  port: 3000,
  fetch(request) {
    return new Response("Hello from Bun!");
  },
});

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

Bun Exclusive Features

Native Hot Reload (new in 1.3):

# Completely replaces nodemon
bun --hot run server.js

Integrated bundler:

// Native bundling - no webpack/vite needed
await Bun.build({
  entrypoints: ['./src/index.ts'],
  outdir: './dist',
  minify: true,
  sourcemap: 'external',
});

Native SQLite:

import { Database } from "bun:sqlite";

const db = new Database("mydb.sqlite");
db.run("CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT)");

const insert = db.prepare("INSERT INTO users (name) VALUES (?)");
insert.run("Alice");

const users = db.query("SELECT * FROM users").all();
console.log(users);

Integrated testing:

// math.test.js
import { expect, test, describe } from "bun:test";

describe("Math", () => {
  test("addition", () => {
    expect(2 + 2).toBe(4);
  });

  test("multiplication", () => {
    expect(3 * 3).toBe(9);
  });
});

bun test

Deno 2.5: Security First

Deno Differentiator

Created by Ryan Dahl (the same creator of Node.js), Deno was designed to fix Node "mistakes":

// server.ts - Native TypeScript in Deno
Deno.serve({ port: 3000 }, (req) => {
  return new Response("Hello from Deno!");
});

Permission System

# Deno explicitly asks permission to access resources
deno run --allow-net --allow-read server.ts

# Granular permissions
deno run --allow-net=api.example.com --allow-read=./data server.ts

Available permissions:

• --allow-net: Network access
• --allow-read: File reading
• --allow-write: File writing
• --allow-env: Environment variables
• --allow-run: Execute subprocesses

Native TypeScript

// No configuration - works immediately
interface User {
  id: number;
  name: string;
  email: string;
}

async function fetchUser(id: number): Promise<User> {
  const response = await fetch(`https://api.example.com/users/${id}`);
  return response.json();
}

const user = await fetchUser(1);
console.log(user.name);

npm Compatibility

Deno 2.x brought compatibility with npm packages:

// Importing npm packages in Deno
import express from "npm:express";
import lodash from "npm:lodash";

const app = express();
app.get("/", (req, res) => {
  res.send(lodash.capitalize("hello world"));
});

Node.js 24: The Reliable Veteran

Why Node.js Still Matters

With over 15 years of existence, Node.js has:

• Mature ecosystem: Millions of packages on npm
• Enterprise support: Adopted by all major companies
• Stability: LTS with long-term support
• Documentation: Years of tutorials, courses and solutions

// server.js - Traditional Express
import express from 'express';

const app = express();

app.get('/', (req, res) => {
  res.send('Hello from Node.js!');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Node.js 24 News

Native watch mode:

node --watch server.js

ES Modules improvements:

// package.json
{
  "type": "module"
}

// Now imports work natively
import { readFile } from 'fs/promises';

Experimental TypeScript support:

# Still experimental, but working
node --experimental-strip-types app.ts

When to Use Each Runtime

Use Bun When:

Ideal for:

• Startups and greenfield projects
• Applications that need maximum performance
• Rapid development with hot reload
• Projects that want integrated bundling

// Complete setup with Bun in seconds
bun init
bun add express
bun --hot run index.ts

Companies using Bun:

• Midjourney
• Vercel (Edge Functions)
• Cloudflare Workers

Use Deno When:

Ideal for:

• Applications with strict security requirements
• Edge/serverless environments
• TypeScript-first projects
• Teams that value web standards

// Deploy to Deno Deploy in one command
deployctl deploy --project=my-app main.ts

Use cases:

• APIs in regulated environments
• Edge computing
• Secure automation scripts

Use Node.js When:

Ideal for:

• Enterprise projects with stability requirements
• Teams with existing Node experience
• Integration with legacy systems
• Access to complete npm ecosystem

# Thousands of tutorials and solutions available
npm init -y
npm install express mongoose redis

Migrating Between Runtimes

From Node.js to Bun

In most cases, just swap the command:

# Before
npm install
node index.js

# After
bun install
bun run index.js

Compatibility:

• 95%+ of npm packages work
• Node.js APIs implemented (fs, path, http, etc.)
• package.json works the same

From Node.js to Deno

Requires more adaptations:

// Node.js
const fs = require('fs');
const data = fs.readFileSync('./file.txt', 'utf8');

// Deno
const data = await Deno.readTextFile('./file.txt');

// Or using compat
import { readFileSync } from "node:fs";
const data = readFileSync('./file.txt', 'utf8');

Conclusion

In 2025, there is no "best" runtime - there is the most suitable for your use case:

• Maximum performance? Bun
• Security first? Deno
• Enterprise stability? Node.js

Most importantly, competition between the three is raising the level of the entire JavaScript ecosystem. Features that Bun introduced are being incorporated into Node.js. Deno security standards are influencing the entire industry.

If you want to understand more about changes in the JavaScript ecosystem, I recommend checking out the article about TypeScript dominating the market in 2025 where you will discover why TypeScript has become standard in all these runtimes.

Lets go! 🦅