Using Bun for Full-Stack Development: Pros and Cons

Introduction

Bun positions itself as an all-in-one runtime that combines a JavaScript engine, a bundler, and a package manager. For teams building full-stack applications, Bun promises faster iterations, a simpler toolchain, and an integrated development experience. This post breaks down the main advantages and the trade-offs you should consider when evaluating Bun for a full-stack workflow.

What Bun is

Bun is a modern JavaScript runtime inspired by the needs of fast developers: a fast runtime, a built-in bundler, and a high-speed package manager. It aims to be a drop-in replacement for many Node.js tasks, with first-class support for TypeScript, zero-config tooling, and a dev server. In a full-stack setup, Bun can power backend APIs and work with frontend tooling, either directly or alongside existing frontend frameworks.

Pros of using Bun for full-stack development

• Speed and performance
  • Very fast startup times and dev server responsiveness.
  • The integrated bundler can reduce build times compared to traditional toolchains.
• Unified DX
  • A single toolchain governs dependencies, scripting, and dev workflows.
  • Built-in TypeScript support reduces configuration friction.
• Efficient package management
  • Bun’s package manager is designed to be fast and cache-friendly, accelerating install steps.
• Great for prototyping and small-to-medium projects
  • Quick setup and iteration cycles help teams validate ideas faster.
• Monorepo-friendly tooling
  • Bun can simplify scripts and tooling across multiple packages within a monorepo.

Cons and trade-offs

• Ecosystem maturity and compatibility
  • While many Node.js packages work well with Bun, some libs rely on Node-specific features or native binaries that may require workarounds.
• Framework and ecosystem gaps for some stacks
  • SSR frameworks and certain production-grade deployments may have less established Bun support or require extra configuration.
• Debugging and observability
  • Debugging experience can be different from Node-centric toolchains; some developers may need to adjust their workflows.
• Production readiness and hosting
  • Not all hosting environments or CI pipelines are optimized for Bun out of the box; you may need to validate compatibility with your stack.
• Bundling nuances
  • Bun’s bundler is fast, but there can be edge-case differences versus established bundlers like Webpack or esbuild. Some advanced configurations may require testing.

Practical use cases

• API services and microservices that benefit from fast start-up times and simpler setups.
• Prototyping full-stack ideas where you want a tight feedback loop with a single toolchain.
• CLI tools and developer tooling that can leverage Bun’s runtime and speed.
• Small to medium projects where you don’t rely heavily on niche Node modules with native bindings.

Getting started quick-start

• Install Bun
  • Run: curl -fsSL https://bun.sh/install | bash
  • Follow any on-screen prompts to add Bun to your PATH.
• Create a new project
  • bun init my-app
  • cd my-app
• Add a backend dependency (example: Express)
  • bun add express
• Create a simple API (example: index.js)
  • Code:
    • import express from ‘express’;
    • const app = express();
    • app.get(’/’, (req, res) => res.send(‘Hello from Bun!’));
    • app.listen(3000, () => console.log(‘Server listening on port 3000’));
• Run the dev server
  • bun dev
• Notes
  • You can also use bun x for running CLI tools or bun run for script execution.
  • For frontend work, Bun can complement your existing frontend tooling or serve lightweight static assets, depending on your stack.

When to consider Bun for a full-stack project

• You prioritize speed in development and want a simplified toolchain.
• Your backend is compatible with Bun’s runtime and you don’t rely on Node-only native addons.
• You’re prototyping or building microservices where rapid iteration outweighs the need for every edge-case feature of Node-dominated ecosystems.
• You’re comfortable validating compatibility with your hosting and CI environment.

Conclusion

Bun offers compelling advantages for full-stack development, especially around speed and developer experience. It shines in prototyping and smaller to mid-sized projects where a unified toolchain can reduce friction. However, it isn’t a one-size-fits-all replacement for every Node-based stack. Before adopting Bun for production workloads, assess ecosystem compatibility, hosting and CI requirements, and how your chosen frameworks and libraries interact with Bun’s runtime and bundling approach.