What is Bun? A Fast Runtime Node.js Alternative

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Matheus Berkenbrock
Senior Full-stack Developer
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Originally published on Nov 23, 2023Last updated on Dec 12, 2023

Key Takeaways

What is bun JS used for?

Bun is an “all-in-one JavaScript toolkit” that ships as a single executable called bun. It's built on top of JavaScriptCore, the JS engine behind Safari, which tends to start faster and be more memory efficient than V8.

Is Bun really faster than Deno?

Bun was shown to be three times faster at server-side rendering in React than either Node.js and Deno. When it comes to handling queries per second, Bun is nearly two times faster than Deno.

Why use Bun instead of node?

Consider using Bun instead of Node.js for a more streamlined and efficient development experience. Node.js, being the pioneering server-side JavaScript runtime, introduced challenges such as slow build and test times, a complex development environment, inefficient package management, and slow ESM adoption. In response, Bun emerges as a modern, drop-in replacement with cohesive tooling, tackling these issues head-on.

Is Bun compatible with node?

Bun aims to be a drop-in replacement for Node.js. Because Node.js is so widespread, it would be difficult to adopt a whole new approach. Instead, Bun natively implements the majority of Node.js APIs, prioritizing the most-used developers, such as fs, path, and Buffer.