Bun Package Manager: O Runtime JavaScript Mais Rápido em 2026

Bun é um runtime JavaScript tudo-em-um escrito em Zig. Seu gerenciador de pacotes instala dependências até 23x mais rápido que o npm.

Instalação e comandos básicos

Bun instala em segundos e funciona como substituto direto dos comandos npm.

# Install Bun
curl -fsSL https://bun.sh/install | bash

# Verify installation
bun --version  # 1.x.x

# Install dependencies (reads package.json)
bun install

# Install a specific package
bun add express
bun add -d typescript @types/node   # dev dependency
bun add -g bunx                     # global install

# Remove a package
bun remove lodash

# Update all packages
bun update

# Run a script from package.json
bun run build
bun run dev

# Execute a TypeScript file directly (no transpile step)
bun run index.ts

Workspaces (suporte a monorepo)

Bun suporta workspaces no estilo npm para monorepos.

// package.json — monorepo root
{
  "name": "my-monorepo",
  "workspaces": [
    "packages/*",
    "apps/*"
  ],
  "scripts": {
    "dev": "bun run --filter '*' dev",
    "build": "bun run --filter '*' build",
    "test": "bun test"
  }
}

// Run a script only in specific workspace
bun run --filter @myapp/web dev

// Install a dependency in a specific workspace
bun add react --cwd apps/web

// Link a local workspace package
// (Bun automatically resolves workspace: protocol)

O arquivo de lock binário (bun.lockb)

Bun usa um arquivo de lock binário em vez de JSON.

# bun.lockb is a binary lockfile (much faster to parse than JSON)
# To view lockfile contents in human-readable form:
bun bun.lockb  # prints as yarn.lock format

# To regenerate lockfile:
bun install --frozen-lockfile  # CI: fails if lockfile is stale

# Migrating from npm/yarn/pnpm:
# Bun reads package-lock.json, yarn.lock, pnpm-lock.yaml
# to preserve existing versions on first install

# .gitignore for Bun:
# node_modules/
# *.lock  (optional — commit bun.lockb for reproducible installs)

Benchmarks de desempenho

O gerenciador de pacotes do Bun é substancialmente mais rápido que todas as alternativas.

# Benchmark: installing react + 1400 packages
# (warm cache, MacBook M2 Pro)

npm install:   28.3s
yarn install:  14.1s
pnpm install:   9.4s
bun install:    1.2s   # 23x faster than npm!

# Cold cache (first install, no node_modules)
npm install:   38.7s
bun install:    4.1s   # 9x faster

# bun install uses:
# - Symlink-based node_modules (like pnpm)
# - Binary lockfile (bun.lockb) for fast parsing
# - Parallel downloads
# - Global package cache (~/.bun/install/cache)
# - Native code (written in Zig)

bunx e ferramentas integradas

bunx executa pacotes sem download usando binários em cache.

# bunx — like npx but instant (no download delay)
bunx create-next-app@latest my-app
bunx prettier --write .
bunx eslint src/

# Run TypeScript directly
bun index.ts            # works without ts-node or compilation
bun --watch server.ts   # auto-restart on file changes

# Bun's built-in test runner (Jest-compatible API)
bun test
bun test --watch
bun test src/utils.test.ts

// Example test file
import { expect, test, describe } from 'bun:test';

describe('math', () => {
    test('adds numbers', () => {
        expect(1 + 2).toBe(3);
    });

    test('async operations', async () => {
        const result = await fetch('https://api.example.com/data');
        expect(result.ok).toBe(true);
    });
});

Scripts e integração de build

Bun executa scripts do package.json mais rápido que npm/yarn.

// package.json scripts with Bun
{
  "scripts": {
    "dev": "bun --watch src/index.ts",
    "build": "bun build src/index.ts --outdir dist --target node",
    "bundle:web": "bun build src/app.ts --outdir public/js --target browser --minify",
    "test": "bun test",
    "lint": "bunx eslint src/",
    "format": "bunx prettier --write src/"
  }
}

// Bun's built-in bundler (replaces esbuild/webpack for simple cases)
// bun build src/index.ts --outdir dist --target node --minify

// Environment variables (Bun auto-loads .env files)
// No need for dotenv package!
console.log(process.env.DATABASE_URL); // works in Bun automatically

Bun vs npm vs pnpm vs Yarn

Boas práticas

• Fazer commit do bun.lockb para instalações reproduzíveis.
• Usar bun --watch para desenvolvimento.
• Migrar progressivamente do npm.
• Para monorepos, combinar Bun workspaces com Turborepo.
• Bun carrega .env automaticamente — sem necessidade de dotenv.

Perguntas frequentes