Bun

JavaScript is the programming language in which almost all interactive websites are written. Originally it only ran in the browser. For such code to also run on a normal computer or on a server, an additional program is needed, a so-called runtime environment. Bun is such a runtime environment: you hand it a file with JavaScript code, and it executes it. Bun was started in 2021 by the developer Jarred Sumner and released in a first stable version in 2023. Its big competitor is called Node.js and has existed since 2009.

Why developers care about speed and an all-in-one package

Anyone who writes software is constantly waiting. Code has to be started, transformed, and tested, often hundreds of times a day. Bun promises exactly here seconds instead of minutes. For some tasks, such as installing external code building blocks, it is, according to its own measurements, several times faster than the established tools.

The second point is bundling. In the JavaScript world, it is common to use a separate program for each sub-task: one for installing libraries, one for testing, one for packaging the code for the browser. These tools have to be set up and coordinated with each other. Bun brings all of this together in a single program. For beginners this means less configuration, for companies fewer components that can break.

Bun is therefore also an economic topic. Behind the project is the company Oven, which has raised venture capital. If server programs run faster, less computing power is needed, which lowers cloud bills. This is exactly what the project advertises.

JavaScriptCore, Zig, and Node compatibility

Every JavaScript runtime environment needs an engine that translates the code into machine instructions. Node.js uses V8, the engine from Google's Chrome browser. Bun instead uses JavaScriptCore, the engine from Apple's Safari browser. This engine starts faster in many cases, which is clearly noticeable with short-lived programs.

The rest of Bun is written in the young programming language Zig. Zig works very close to the hardware and leaves control over memory to the programmer. This is more laborious to write but allows for very lean code. In addition, the team has rewritten many features itself instead of adopting ready-made building blocks. Shorter internal paths are a key reason for the measured advantages.

Also important is compatibility with Node.js. Bun tries to replicate Node’s commands and libraries so that existing projects run without rewriting. This does not fully succeed, especially with rarely used features there are gaps. A common misconception is that Bun is simply a faster version of Node. It is its own program that merely strives to be compatible.

Bun in projects, job postings, and the debate about Node alternatives

Bun is directly visible only to people who program. You install it and then type commands like bun run or bun install into the command line. In web development tutorials it now regularly appears alongside Node.js. It is also occasionally mentioned in job postings for web developers.

In tech news, the name is usually encountered in connection with the competition among runtime environments. Besides Node.js and Bun, there is Deno, another project with a similar goal. Reports revolve around speed comparisons, funding rounds, or the question of whether large companies are switching. Such comparisons should be read with caution, since measurements depend heavily on the chosen task.

Indirectly, ordinary users ultimately benefit as well. Many websites and apps are built with such tools. Faster tools mean shorter development cycles and, for servers, lower power consumption per request.