Why Bun Wins for Me

Bun has become my go-to JavaScript runtime for new projects—and it's not just about speed. It's about how much friction it removes from the development process. After years of juggling Node.js, Deno, and various toolchains, Bun feels like the runtime I always wanted.

All-in-One Simplicity

Bun isn't just a runtime; it's a full toolkit:

• Runtime: JavaScript and TypeScript execution
• Package Manager: Blazing fast bun install
• Bundler: Native support for JSX, CSS, and more
• Test Runner: Performance that rivals Jest

It also supports TypeScript out of the box, with no need for tsc or additional configuration. You can run .ts and .tsx files directly, and Bun handles transpilation internally.

This consolidation means fewer dependencies and less configuration. No more stitching together tsc, jest, esbuild, and npm—Bun handles it all seamlessly.

Performance That Matters

Bun is built with Zig and uses JavaScriptCore (Safari's engine) instead of V8. This architectural choice translates to real-world speed gains:

• HTTP servers in Bun can handle over 52,000 requests per second, outperforming both Node.js and Deno
• Cold start times are over 60% faster than Node.js

These improvements aren't just benchmarks—they lead to snappier development cycles and more responsive applications.

Thoughtful Node.js Compatibility

Bun aims for near drop-in compatibility with Node.js, supporting CommonJS, ESM, and many Node APIs. This means migrating existing projects or integrating with the vast npm ecosystem is straightforward. While some edge cases exist, the compatibility layer is robust and continually improving.

Bun stands out by offering an integrated experience with high performance and strong Node.js compatibility, reducing the need for additional tools and configurations.

Built-in WebSocket Support

Bun includes native WebSocket support out of the box, offering a low-latency, high-performance interface for real-time applications. The WebSocket API in Bun is straightforward and closely mirrors the browser and Node.js implementations. This means you can quickly spin up WebSocket servers and clients without needing external libraries.

For example:

const server = Bun.serve({
  fetch(req, server) {
    if (server.upgrade(req)) return;
    return new Response("Upgrade required", { status: 426 });
  },
  websocket: {
    open(ws) {
      ws.send("Hello from Bun WebSocket server!");
    },
    message(ws, message) {
      ws.send(`Echo: ${message}`);
    },
    close(ws) {
      console.log("WebSocket closed");
    },
  }
});

This native support allows for leaner applications and faster development when building chat apps, live feeds, or multiplayer game backends.

The One Gotcha: Monorepo nohoist Support

While Bun excels in many areas, it currently lacks support for the nohoist feature in monorepos. This can lead to issues when multiple versions of the same package are needed across different workspaces. For example, in a monorepo structure, Bun tends to hoist all dependencies to the root node_modules, which isn't always desirable. This limitation has been acknowledged by the Bun team and is tracked in their issue tracker.

For projects that rely heavily on nohoist, tools like Yarn or pnpm might still be necessary until Bun addresses this feature.

Final Thoughts

Bun represents a significant step forward in JavaScript runtime development. Its integrated approach simplifies the developer experience, and its performance gains are tangible. While it has some areas to mature, particularly in monorepo support, it's a compelling choice for modern JavaScript and TypeScript projects.

For developers seeking a streamlined, high-performance environment, Bun is well worth exploring.