Skill of the Month – Bun

What is Bun? 

Bun is a fast, all-in-one JavaScript runtime built from the ground up as a modern alternative to Node.js. It’s designed to run JavaScript and TypeScript natively, but it goes further than just being a runtime – it also replaces npm as a package manager, bundles your code, and runs your tests, all from a single tool. The goal is to reduce the number of moving parts in a typical JavaScript project while making everything significantly faster in the process.

Under the hood, Bun is built on JavaScriptCore (the engine behind Safari) rather than V8, and is written in Zig – choices that contribute to its notably quick startup times and overall performance. It’s compatible with the Node.js ecosystem, meaning most existing packages and frameworks work with it out of the box, which lowers the barrier to trying it considerably.

What are some things to know about Bun?

• Speed that’s hard to ignore – Bun consistently benchmarks significantly faster than Node.js across package installs, server throughput, and cold start times. For teams where performance and developer experience matter, the difference is tangible rather than theoretical.

• One tool instead of four – Bun replaces your runtime, package manager, bundler, and test runner in a single install. That consolidation reduces toolchain complexity and cuts down on the configuration overhead that tends to accumulate in JavaScript projects over time.

• Node.js compatibility without a full rewrite – Bun supports Node.js APIs and the npm ecosystem, so teams can adopt it incrementally. You don’t need to overhaul your codebase to benefit from it, which makes it a realistic option for existing projects, not just greenfield ones.

Why learn Bun?

JavaScript tooling has long been a source of frustration – slow installs, fragmented toolchains, and configuration that takes longer to set up than the project itself. Bun is a genuine attempt to fix that, and it’s gaining real traction. It crossed 1.0 in late 2023 and has been steadily building adoption since, with a growing number of teams using it in production.

For JavaScript and TypeScript engineers, familiarity with Bun is becoming a useful differentiator. As more companies look to modernise their frontend and backend JS stacks, knowing your way around Bun – and being able to speak to when and why you’d reach for it – is increasingly worth having. It’s also a strong signal to employers that you’re keeping up with where the ecosystem is heading.

Use Cases for Bun

• Replacing Node.js in backend API and server-side rendering projects for performance gains

• Speeding up CI/CD pipelines through faster package installs and test runs

• Simplifying JavaScript toolchains in monorepos and large frontend projects

• Running TypeScript directly without a separate transpilation step

• Greenfield full-stack JavaScript projects where a clean, fast setup is a priority

• Edge and serverless environments where cold start time is a constraint

Topic of the Month

Is the Node.js Era Coming to an End?

Node.js has been the backbone of server-side JavaScript for the better part of fifteen years. It democratised backend development for frontend engineers, helped build some of the most widely used applications on the internet, and spawned an ecosystem of millions of packages. That’s a legacy worth acknowledging. But the JavaScript world moves quickly, and the tools that defined one era don’t always define the next.

Bun represents the most credible challenge to Node.js dominance that the ecosystem has seen. It’s not the first alternative – Deno arrived a few years ago with similar ambitions – but where Deno asked developers to leave the npm ecosystem behind, Bun largely works within it. That pragmatism matters. It means teams can experiment without committing, and adopt gradually rather than all at once. The performance numbers are real, the developer experience improvements are tangible, and the momentum behind it has been building consistently since its stable release.

Whether Bun displaces Node.js entirely is an open question, and probably not one that needs answering right now. What’s clearer is that the era of accepting slow installs, bloated toolchains, and unnecessary complexity in JavaScript development is running out of road. Bun is pushing the whole ecosystem to move faster – and even if Node.js adapts and closes the gap over time, the pressure Bun is applying is already producing results. For engineers and the teams hiring them, that’s the trend worth watching.

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