Bun

What is Bun?

Bun is a JavaScript runtime, the thing that executes JavaScript and TypeScript outside a browser. It competes with Node.js and Deno, but it bundles far more into one tool. A package manager, a bundler, a test runner, and a runtime, all in a single binary. The selling point is speed. Bun is written in a low-level language called Zig and built on Apple's JavaScriptCore engine rather than Google's V8, and it starts up and installs dependencies noticeably faster than Node.

It launched a stable 1.0 in 2023 and aims to be a near drop-in replacement for Node, supporting most npm packages and Node APIs. Where Node grew a sprawling tooling ecosystem around it over fifteen years, with separate tools for package management, bundling, and testing, Bun's bet is that one fast, integrated tool beats stitching many together. A startup spinning up a new API can install dependencies, run tests, and serve the app using Bun alone, trimming both build times and the number of tools the team has to reason about.

The honest picture: Bun is young. Node remains the safe default for production at scale because of its maturity and battle-tested ecosystem, while Bun shines in development speed and greenfield projects where its rough edges are acceptable.

Bun at Dallonses

We use Bun where its speed pays off without the maturity gap biting us, which often means local development, tooling, and new projects that can absorb a little risk. Faster installs and faster test runs add up across a team, and the integrated toolchain means fewer moving parts to configure and maintain.

For production systems that need to be boringly reliable, we still lean on Node unless a client has a clear reason to switch. We track where Bun is solid and where it is still catching up, and we make that call with clients on evidence rather than novelty. Picking the right runtime is an engineering decision, and we treat it like one.

Curious whether Bun fits your stack? Let's dig in together.

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