belgie 0.23.2

A minimal, secure javascript runtime for python

Belgie: A secure JavaScript runtime for Python, powered by Deno

Belgie lets you run JavaScript and TypeScript from Python. Deno is bundled — you do not need Node.js or Deno on your PATH.

• Scripts from Python: Run inline or file-based JS/TS with Runtime and Script, sync or async.
• Isolated packages: Add npm or JSR deps in Environment; installs live in temp storage, not your repo.
• CLI tools: Run npm binaries (Vite, esbuild, etc.) through Command.
• Simple data bridge: Pass JSON-safe dicts, lists, and primitives across the boundary.

Installation

uv add belgie
uvx library-skills install  # optional: install the use-belgie skill for Cursor, Codex, Claude, etc.

uv add belgie adds the library (Python >=3.12,<3.15, no runtime Python deps).

uvx library-skills install is optional. It links the bundled use-belgie agent skill into .agents/skills/ so coding agents can follow belgie's public API when you work on integrations. Skip it if you only need the Python library.

Quick Start

import asyncio

from belgie import Environment, Runtime, Script

script = Script(
    """
import camelcase from "camelcase";

export default function run(input) {
  return camelcase(input);
}
"""
)

async def main() -> None:
    async with Environment({"camelcase": "npm:camelcase@8.0.0"}) as env:
        await env.install()
        async with Runtime(env=env) as run:
            print(await run(script)("foo-bar"))  # prints: fooBar

asyncio.run(main())

Examples

• simple: Async Runtime with a TypeScript file on disk.
• jsr-deps: JSR packages declared inline in Environment.
• environment: Sync and async Environment setup with cwd.
• commands: npm package binaries via Runtime and Command.

For deeper integration guidance, optionally install the use-belgie skill with uvx library-skills install.