high-speed runtime

Bun

Bun is a modern all-in-one JavaScript runtime, bundler, transpiler, and package manager built from scratch in Zig.

What the product actually does

Bun replaces Node.js, npm, npx, ts-node, and Webpack with a single native binary compiled using the Zig systems language and Apple's WebKit JavaScriptCore engine.

It provides instant TypeScript and JSX execution without configuration, ultra-fast package installation via global hardlinks, and high-throughput native HTTP and SQLite APIs.

How pricing works once you are inside

Bun is free, open-source software. Hosting costs depend on whether it is deployed on bare cloud VMs, Docker containers, or containerized serverless runtimes.

Where it breaks down

While compatibility with Node's standard library is high, obscure C++ native addons and specialized internal Node APIs may encounter compatibility gaps.

What switching costs

Very low. Bun is designed as a drop-in replacement for Node.js projects, allowing instant fallback to Node if edge cases occur.

Sources

Bun official documentation, release benchmarks, and API documentation, October 2026.