Bun vs esbuild vs SWC (2026)
JavaScript build tools were painfully slow until esbuild and SWC rewrote them in faster languages. Now Bun includes a bundler too. Here's how they compare.
Quick Comparison
| Feature | Bun | esbuild | SWC |
|---|---|---|---|
| Language | Zig | Go | Rust |
| Type | Runtime + bundler | Bundler | Transpiler + bundler |
| Speed | Fastest | Very fast | Very fast |
| Tree Shaking | ✅ | ✅ | ⚠️ Basic |
| CSS Bundling | ✅ | ✅ | ❌ |
| TypeScript | ✅ Native | ✅ Strip types | ✅ Strip types |
| JSX | ✅ | ✅ | ✅ |
| Plugins | ✅ JS API | ✅ Go + JS API | ✅ Rust + JS API |
| Used By | Bun projects | Vite (under hood) | Next.js (under hood) |
| Maturity | Newer | Stable | Stable |
Bun — The All-in-One
Bun isn't just a bundler — it's a JavaScript runtime with a built-in bundler, transpiler, test runner, and package manager.
# Bundle
bun build ./src/index.ts --outdir ./dist --minify
# With config
bun build --entry-points ./src/index.ts --outdir ./dist \
--target browser --minify --splitting
Pros: Fastest benchmarks, native TypeScript, all-in-one toolchain. Cons: Newer, smaller ecosystem, some Node.js incompatibilities.
esbuild — The Vite Engine
esbuild is the bundler behind Vite. Written in Go, focused on speed.
// esbuild.config.js
import { build } from 'esbuild'
await build({
entryPoints: ['src/index.ts'],
bundle: true,
minify: true,
sourcemap: true,
target: ['es2020'],
outdir: 'dist',
format: 'esm',
splitting: true,
})
Pros: Battle-tested (powers Vite), stable API, excellent plugin ecosystem. Cons: Doesn't do type checking, limited CSS handling (improving).
SWC — The Next.js Engine
SWC is primarily a transpiler (Babel replacement) written in Rust. It powers Next.js compilation.
// .swcrc
{
"jsc": {
"parser": { "syntax": "typescript", "tsx": true },
"target": "es2020"
},
"module": { "type": "es6" }
}
Pros: Fastest transpilation, powers Next.js, Rust-based plugin system. Cons: Bundler (swcpack) is less mature, primarily a transpiler.
Speed Benchmarks
Transpiling 10,000 TypeScript files:
| Tool | Time |
|---|---|
| Bun | ~0.3s |
| esbuild | ~0.4s |
| SWC | ~0.5s |
| Babel | ~15s |
All three are 30-50x faster than Babel. The differences between them are negligible in practice.
When to Use Each
| Scenario | Choose |
|---|---|
| Using Bun runtime | Bun bundler |
| Using Vite | esbuild (default) |
| Using Next.js | SWC (default) |
| Custom bundler setup | esbuild |
| Replacing Babel | SWC |
| Maximum speed | Bun |
The Real Answer
You probably don't choose directly. Your meta-framework chooses for you:
- Next.js → SWC (built-in)
- Vite → esbuild (built-in)
- Bun projects → Bun bundler
If building a custom setup, use esbuild. It has the most stable API and largest plugin ecosystem.
FAQ
Do I need to replace Webpack?
If you're using Next.js or Vite, you're already using SWC/esbuild. If still on raw Webpack, switch to Vite (which uses esbuild).
Can esbuild do type checking?
No. None of these tools do type checking. Run tsc --noEmit separately for type checks.
Is Bun's bundler production-ready?
For most use cases, yes. Large production apps may hit edge cases. esbuild is more battle-tested.
Bottom Line
All three are excellent and 30-50x faster than Babel/Webpack. Use what your framework chooses: SWC for Next.js, esbuild for Vite, Bun for Bun projects. For custom setups, default to esbuild.