Bun.js vs Node.js

Introduction

In the world of JavaScript runtimes, Node.js has long been the default choice. But with the arrival of Bun.js, developers are exploring faster, more modern alternatives. If you're wondering how these two compare, this blog breaks down the key differences between Bun.js and Node.js in terms of speed, features, architecture, and developer experience.

Overview of Node.js

Node.js is a widely adopted JavaScript runtime built on Chrome's V8 engine. It allows developers to run JavaScript outside the browser, making it ideal for building backend services, APIs, and full-stack apps. Node.js has a massive ecosystem powered by npm and supports an asynchronous, event-driven architecture.

Overview of Bun.js

Bun.js is a relatively new JavaScript runtime built from scratch using the Zig programming language. Its goal is to offer a fast, all-in-one toolset for modern development. Bun includes a JavaScript runtime, bundler, test runner, and package manager—no need to install separate tools like Webpack, Jest, or npm.

Performance Comparison

Performance is where Bun shines. Benchmarks show that Bun.js executes JavaScript significantly faster than Node.js in most scenarios, thanks to low-level optimizations from Zig and efficient system calls.

// Node.js
console.time("node");
for (let i = 0; i < 1e6; i++) {}
console.timeEnd("node");

// Bun.js
console.time("bun");
for (let i = 0; i < 1e6; i++) {}
console.timeEnd("bun");

In many tests, Bun's runtime executes loops and synchronous code up to 2x faster than Node.

Bundling and Transpilation

Node.js requires third-party tools like Babel and Webpack for transpiling JSX or TypeScript and bundling assets. Bun, on the other hand, comes with built-in support for these out of the box.

// Bun.js can bundle TypeScript directly
bun build index.ts --outfile=bundle.js

This makes Bun a better choice for developers who prefer minimal setup and faster builds.

Package Management

Node.js relies on npm or yarn for dependency management. While powerful, they can be slow when installing packages. Bun has its own package manager, which is incredibly fast due to parallel downloads and native caching.

// Install with Bun
bun add express

// Install with npm
npm install express

Bun can install packages in seconds—even large ones like React or Angular.

Built-in Features

Ecosystem and Stability

Node.js has a mature ecosystem with millions of packages and community support. It’s used in production by companies like Netflix, LinkedIn, and PayPal. Bun, while growing rapidly, is still young and may not yet support every Node.js module or edge case.

Developer Experience

Bun was built with developer happiness in mind. It requires fewer tools, minimal setup, and supports hot reloading, faster install times, and simpler configuration files. Node.js is extremely powerful but often requires piecing together multiple tools.

Use Case Recommendations

• Use Node.js if you need long-term support, large-scale production readiness, or compatibility with legacy tools.
• Use Bun.js if you're starting a new project, care about performance, and want modern tooling without extra config.

Conclusion

Both Node.js and Bun.js have their place in the JavaScript ecosystem. While Node remains the trusted and established option, Bun is an exciting new player offering modern solutions with speed and simplicity. Developers building high-performance apps or experimenting with modern tooling should definitely give Bun.js a try.

As the ecosystem matures, we can expect Bun.js to challenge Node.js even more directly. The future of JavaScript runtimes is fast, and Bun is leading the charge.