biu

⚡ zero-config bundler · powered by Bun

A zero-config, high-performance bundler for HTML + TypeScript/JavaScript, powered by Bun. Smart module splitting, content hashing, watch mode, dev server, optional Next.js-style backend, and offline CDN caching — all in one binary.

Install

$ curl -fsSL https://mindon.dev/biu/install | bash

Quick Start

# Place `biu` in your PATH, then from any project directory:
biu                        # Build ./src → ./dist
biu ./src ./dist           # Explicit source & output dirs
biu --serve 3000           # Dev server with live reload

Note: if there's a ./backend directory, it will be used as Next.js-style backend.

Command Syntax

biu [options] [srcDir] [outDir]

Argument	Default	Description
`srcDir`	`./src`	Source directory
`outDir`	`./dist`	Output directory

Options

Option	Description
`--watch`	Watch mode — rebuild on file changes
`--static <dir>`	Static assets directory (default: `./static`)
`--post-build <file>`	Run `.sh`/`.ts`/`.js` script after each build
`--serve [port]`	Start dev server (default port: `3000`, implies `--watch`)
`--build [outfile]`	Self-compile to standalone binary (default: `./biu`)
`-v, --version`	Show version
`-h, --help`	Show help

Options can appear in any order.

Examples

Basic build

biu ./src ./dist

Watch mode with dev server

biu --serve 8080

Custom static directory + post-build script

biu --static ./public --post-build ./scripts/deploy.sh

Smart Module Splitting

Independent module: if a .ts/.js file's basename (e.g. main.ts) appears in any HTML file, it's built as a separate module with content hash.
Auto inline: if the basename never appears in any HTML, the file is automatically inlined into its importer — no separate output.
Force inline (??): append ?? to force inline bundling:
```
import { myUtil } from "./utils.ts??";
```

Environment Variables

Variable	Description
`BIU_ASSETS_EXTS`	Extra asset extensions, e.g. `"glb,gltf,hdr"`
`BIU_EXCLUDED`	Regex pattern to exclude files, e.g. `"test\|spec"`

Full documentation: github.com/mindon/biu
Issues & feedback: github.com/mindon/biu/issues
License: MIT