Browser Runtime Guide

Run Python in the browser using Pyodide WebAssembly.

Overview

• WebAssembly Python in the browser
• No server required for execution
• Pre-built packages via Pyodide
• Works well for notebooks, demos, and client-side analysis

Quick Start

Install

npm install tywrap pyodide

Configure

{
  "pythonModules": {
    "numpy": { "runtime": "pyodide" },
    "matplotlib": { "runtime": "pyodide" }
  },
  "runtime": {
    "pyodide": {
      "indexURL": "https://cdn.jsdelivr.net/pyodide/v0.28.0/full/",
      "packages": ["numpy", "matplotlib", "scipy"]
    }
  }
}

Use

import { PyodideBridge } from 'tywrap/pyodide';
import { setRuntimeBridge } from 'tywrap/runtime';
import { array } from './generated/numpy.generated.js';

const bridge = new PyodideBridge({
  indexURL: 'https://cdn.jsdelivr.net/pyodide/v0.28.0/full/',
  packages: ['numpy']
});

setRuntimeBridge(bridge);

const arr = await array([1, 2, 3]);
console.log(arr);

Configuration Options

interface PyodideBridgeOptions {
  indexURL?: string;
  packages?: string[];
}

The packages array is loaded during initialization. For additional package loading, rely on Pyodide directly.

Data Transport

Arrow envelopes are supported in the browser if you register an Arrow decoder (Node auto-registers when apache-arrow is installed):

import { registerArrowDecoder } from 'tywrap';

registerArrowDecoder(bytes => bytes);

Build Integration

Run tywrap generate during your build and load Pyodide at runtime (CDN or self-hosted).