Bun Runtime Tutorial: Getting Started in 2026

TL;DR Summary

In today’s fast-evolving JavaScript ecosystem, Bun has emerged as a powerful, all-in-one runtime that combines a runtime, package manager, bundler, and test runner into a single, streamlined tool. Built for speed and efficiency, Bun offers significantly faster startup times and package installations compared to Node.js. In this comprehensive tutorial, we’ll explore everything you need to know to get started with Bun, from installation to running your first project, and dive into its powerful built-in tools.

If you’re a developer who has worked with Node.js, you’ll find that Bun performs a similar role, but with several key advantages. It’s important to note that Bun isn’t just a runtime, it’s an entire toolkit designed to simplify your development workflow. In this guide, we’ll walk you through what Bun is, how to install it, and how to leverage its core features to build robust projects efficiently.

What is Bun?

Bun is a modern JavaScript and TypeScript runtime that aims to be a faster, more efficient alternative to Node.js. Unlike Node.js, which relies on Google’s V8 engine, Bun is powered by Apple’s JavaScriptCore engine, the same engine that drives Safari.

What truly sets Bun apart is its all-in-one nature. Rather than requiring developers to install and configure multiple separate tools, Bun seamlessly integrates:

• A fast and reliable package manager (an alternative to npm or yarn)
• A built-in bundler (similar to Webpack, but faster)
• A native test runner (eliminating the need for Jest)

This means that with Bun, you can install dependencies, write and run your code, execute tests, and bundle your application for production, all from a single, unified tool.

How Bun Compares to Node.js

To better understand Bun’s advantages, let’s take a look at how it stacks up against Node.js across several key metrics:

As you can see, Bun offers substantial improvements across nearly every category, making it an increasingly popular choice among developers in 2026.

How to Install Bun on Your System?

Now that we’ve covered what Bun is and why it matters, let’s walk through the installation process. The good news is that getting Bun up and running takes just a few minutes, regardless of your operating system.

Installing on macOS and Linux

To get started on macOS or Linux, simply open your terminal and run the following command:

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

This command will automatically download and install Bun on your system. Once the installation process is complete, be sure to restart your terminal and verify that everything is working correctly by running:

bun --version

If everything went smoothly, you should see a version number such as 1.3.x, confirming that Bun has been successfully installed.

Installing on Windows

For Windows users, Bun supports both Windows 10 (22H2) and Windows 11. To install it, open PowerShell and run:

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

Once the installation finishes, open a new PowerShell window and run bun –version to confirm that Bun is ready to use.

Creating Your First Bun Project

With Bun successfully installed, you’re now ready to create your first project. Navigate to your desired project folder, and run the following command:

bun init

This will generate a basic project structure, complete with a package.json file and an entry file, typically named index.ts.

Running JavaScript and TypeScript Files

One of the standout features of Bun, especially for beginners, is its native support for TypeScript. This means you don’t need to install or configure a separate compiler to get started.

Let’s create a simple file called hello.ts:

//javascript

console.log("Hello from Bun!");

To run this file, simply execute:

bun run hello.ts

You’ll see the output appear almost instantly. Notice that there was no need for any additional setup, Bun handles everything seamlessly behind the scenes.

Bun’s All-in-One Toolkit

This is where Bun truly shines and differentiates itself from traditional Node.js workflows. Instead of managing multiple separate tools, Bun provides a unified, efficient solution.

Package Manager

Bun’s package manager serves as a fast, reliable, and efficient alternative to npm. Some of the most commonly used commands include:

• bun add express to install a package
• bun add -d typescript to install a development dependency
• bun install to install all dependencies listed in package.json
• bun remove express to remove a package

Additionally, if you’re migrating an existing project, Bun can read your current package.json file directly, eliminating the need for any additional configuration.

Bundler

Once your application is ready for production, Bun’s built-in bundler allows you to compile your code without relying on external tools like Webpack:

bun build index.ts --outdir ./dist

This command efficiently bundles your TypeScript and JavaScript files into optimized, production-ready output.

Built-in Test Runner

Testing is another area where Bun excels. With its native test runner, there’s no need to install Jest or any other external testing library. Here’s a simple example:

//javascript

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

test("adds numbers correctly", () => {

  expect(2 + 2).toBe(4);

});

To run all your tests, simply use:

bun test

Real-World Use Case

In real-world scenarios, startups and development teams are increasingly turning to Bun for backend services where speed and efficiency are critical, such as serverless functions and edge computing applications. 

For instance, a development team building a REST API with Bun and a lightweight framework like Hono can connect directly to databases such as Postgres or Redis using Bun’s built-in drivers, ultimately reducing both setup complexity and the overall number of dependencies required.

Common Mistakes to Avoid

As with any new technology, there are several common pitfalls that beginners should be aware of when working with Bun:

1. Assuming all npm packages work flawlessly: While Bun’s compatibility layer ensures most npm packages function correctly, some packages that rely on Node-specific internals may not behave as expected. Be sure to thoroughly test your dependencies.
2. Using loose version ranges in production: Since Bun evolves rapidly, it’s best to pin a specific version, such as “1.3.11”, rather than using a range like “^1.1.0”, which could lead to unexpected breaking changes.
3. Relying solely on outdated blog tutorials: Given how quickly Bun is evolving, it’s always a good idea to cross-reference commands with the official documentation to ensure accuracy.
4. Mixing package managers inconsistently: Switching back and forth between bun install and npm install within the same project can lead to conflicting lock files and unexpected issues.
5. Overestimating performance gains across the board: While Bun offers significant improvements in startup time and package installation speed, real-world application performance, particularly when database and routing layers are involved, may show a smaller difference compared to Node.js.

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Wrapping Up

Bun represents a significant step forward for JavaScript developers, offering a fast, efficient, and all-in-one solution that streamlines the development process. From its quick and easy installation to its powerful built-in package manager, bundler, and test runner, Bun eliminates much of the setup overhead commonly associated with Node.js. 

As adoption continues to grow throughout 2026, now is the perfect time to start exploring Bun. Begin by installing it, running a simple script, and experimenting with bun init to kickstart your very first project.

FAQs

1. Is Bun a replacement for Node.js?

In most cases, yes, Bun can serve as a replacement for Node.js, as it supports Node.js APIs and npm packages. That said, it’s always a good idea to test any Node-specific packages before moving to production.

2. Do I need to learn TypeScript to use Bun?

Not necessarily. Bun runs plain JavaScript files just as effectively. While TypeScript support is built in, it’s entirely optional.

3. Is Bun free to use?

Yes, Bun is completely open source and free to download and use for any project, big or small.

4. Can Bun run existing Node.js projects?

Generally speaking, yes. Thanks to its Node.js compatibility layer, most existing projects should run with minimal to no changes required.

5. What operating systems does Bun support?

Bun supports macOS 13 and above, Linux distributions with glibc 2.31 or higher, as well as Windows 10 (22H2) and Windows 11.

6. Why is Bun faster than Node.js?

Overall, Bun was designed from the ground up with performance in mind. Its use of the JavaScriptCore engine, combined with an efficient internal architecture, results in significantly faster startup times and quicker package installations.

7. Should beginners start learning with Bun or Node.js?

Ultimately, either option is a great starting point, as the underlying JavaScript concepts remain the same. That said, Bun simplifies the overall setup process by reducing the number of separate tools required.