Bun bundler
Bun isn't just a runtime — it includes a bundler (bun build), test runner (bun test), package manager (bun install), Node-compatible API.
Jarred Sumner built it in Zig. Bundler is esbuild-comparable in speed but with JSX/TSX/CSS-modules support. Bun test ~2-3× faster than Vitest on the same testbed. Critics: API surface is huge, hard to keep stable. 1.0 September 2023, 1.1 March 2024 added Windows support. Competitors: Vite + Vitest (most mature), esbuild (just bundler).