esbuild

esbuild proved that JavaScript bundling didn't have to be slow. Written in Go with aggressive parallelism, it's 10-100x faster than webpack. Vite uses it under the hood for dependency pre-bundling. That tells you everything about its impact.

Vite is the framework most people should reach for — it wraps esbuild and Rollup into a better DX. Webpack is the legacy option with the biggest plugin ecosystem. Turbopack (Vercel) is the Rust-based competitor aiming to replace webpack in Next.js. SWC handles the transpilation side.

Use esbuild directly if you need a fast, zero-config bundler for a library, CLI tool, or simple app. It's MIT licensed, single binary, no dependencies. For anything with complex needs — code splitting, CSS modules, HMR — you'll want Vite on top.

The catch: esbuild intentionally doesn't aim for feature parity with webpack. No HMR built in, limited CSS support, and the plugin API is minimal by design. Evan Wallace built it as a building block, not a complete solution. Also, it's essentially a one-person project — bus factor of one.