Bun 2.0: Should Your Node.js Projects Switch in 2026?

🕮5 min read · 974 words

Bun has been promising to replace Node.js for two years. Bun 2.0 is the version where the conversation gets serious. It’s not a toy anymore — it’s running in production at real companies, it ships 95%+ Node.js compatibility, and the performance numbers are genuinely significant.

But “should you switch” is the wrong question. The right question is “should you switch for your specific use case.” Here’s the honest answer.

What Bun Actually Is

Bun is a JavaScript runtime — like Node.js — but built from scratch in Zig instead of C/C++, using JavaScriptCore (Safari’s engine) instead of V8 (Chrome’s engine). It ships as a single binary that includes:

• JavaScript/TypeScript runtime
• Package manager (replaces npm/yarn/pnpm)
• Bundler (replaces webpack/esbuild)
• Test runner (replaces Jest/Vitest)
• Script runner

One binary. No separate tool for each task. This is Bun’s design philosophy — collapse the JavaScript toolchain into one fast thing.

Bun 2.0 — What Changed

• Node.js compatibility: 95%+ — up from ~85% in Bun 1.x. Most npm packages that work in Node.js now work in Bun unchanged.
• Worker Threads stable — previously unreliable, now production-ready
• Node-API (N-API) support — native Node.js addons can run in Bun. This was the biggest compatibility gap.
• V8 snapshots support — some packages that relied on V8 internals now work
• Improved Windows support — Bun 1.x on Windows was unreliable; 2.0 is significantly better
• SQLite built-in (improved) — native SQLite without any npm package
• Bun Shell — cross-platform shell scripts in JavaScript

The Real Performance Numbers

Bun’s own benchmarks are optimistic. Here are more conservative real-world numbers from community testing:

The package install speed is the number that changes developer experience most immediately. `bun install` on a project that takes 45 seconds with npm takes 8 seconds. In CI/CD where you’re doing this constantly, this is a genuine time and cost saving.

Where Bun Makes Sense Right Now

Development Tooling and Scripts

The safest and highest-value switch: use Bun as your package manager and script runner for existing Node.js projects without changing your runtime.

# In any existing Node.js project
# Replace: npm install → bun install
# Replace: npm run dev → bun run dev
# Replace: npx jest → bun test

# package.json stays the same
# node_modules are still created
# Your Node.js code doesn't change

# Just faster installs and script startup

This works in 99% of projects today with zero risk. The only thing that changes is speed.

New API Projects (Hono + Bun)

Starting a new API server? Hono + Bun is one of the fastest combinations available and entirely production-viable:

bun create hono my-api
cd my-api
bun install
bun run dev

// src/index.ts
import { Hono } from 'hono';

const app = new Hono();

app.get('/', (c) => c.text('Hello from Bun + Hono!'));

app.get('/health', (c) => c.json({
  status: 'ok',
  runtime: process.versions.bun ?? 'node',
}));

export default {
  port: 3000,
  fetch: app.fetch,
};

Scripts and Automation

Replace Node.js scripts with Bun for faster startup:

#!/usr/bin/env bun
// scripts/migrate-data.ts
import { Database } from 'bun:sqlite'; // Built-in SQLite, no npm install

const db = new Database('data.sqlite');

const users = db.query('SELECT * FROM users WHERE migrated = 0').all();
console.log(`Migrating ${users.length} users...`);

// ... migration logic

console.log('Done!');

CI/CD Pipelines

The fastest win: switch your CI install step from npm to bun:

# .github/workflows/ci.yml
- name: Setup Bun
  uses: oven-sh/setup-bun@v2
  with:
    bun-version: latest

- name: Install dependencies
  run: bun install --frozen-lockfile

- name: Run tests
  run: bun test

- name: Build
  run: bun run build

No code changes. Just faster CI runs — typically 30–50% faster overall pipeline time.

Where to Be Careful

Existing Large Node.js Applications

The 5% incompatibility in Bun 2.0 is real and can be painful. Common issues:

• Packages that use __dirname in ESM modules (Node.js-specific behaviour)
• Some native Node.js addons (though N-API support improved significantly)
• Packages that rely on specific Node.js error message formatting
• Some stream implementations behave differently

Before migrating: run your test suite under Bun. If it passes, the migration is probably safe. If tests fail, investigate before deploying to production.

# Test your existing Node.js project with Bun
bun test  # Runs Jest-compatible tests
# Or run your test script
bun run test

Express.js Applications

Express.js itself runs on Bun, but some Express middleware uses Node.js internals. Test specifically:

• Session middleware
• File upload middleware (multer)
• Authentication middleware (passport)

The Honest Assessment

Switch to Bun as package manager immediately: Zero risk, instant benefit, works with any project. `bun install` instead of `npm install` is the easiest performance win in the JavaScript ecosystem right now.

Use Bun runtime for new TypeScript/JavaScript API projects: Hono + Bun is production-ready and excellent. Good choice for new projects where you’re not constrained by existing dependencies.

Migrate existing production Node.js apps carefully: Run your test suite under Bun first. If everything passes, migration is probably safe. If tests fail, those failures indicate real compatibility issues. Don’t migrate without a solid test suite.

For Laravel backends (PHP): Bun replaces npm for your frontend assets. Use `bun install` instead of `npm install` in your Laravel projects. Run `bun run build` instead of `npm run build`. This works today with Vite + Laravel Plugin with no changes required.

# In your Laravel project — just use bun instead of npm
bun install           # Instead of npm install
bun run dev           # Instead of npm run dev
bun run build         # Instead of npm run build

# Everything else stays the same

If you’re setting up a new JavaScript API project or want advice on modernizing your build toolchain, our team at Softcrony is happy to help.