WebContainers

WebContainers is a browser-based runtime that lets you run Node.js directly in the browser. It allows developers to embed full-stack development environments into web applications without connecting to external servers. You can run native package managers like npm and pnpm, execute server-side code, and create interactive coding experiences that work entirely within the user's browser.

The technology works by creating secure, sandboxed containers that run in the browser using WebAssembly and other modern web APIs. What makes WebContainers stand out is its ability to run actual Node.js processes—not just simulations—with direct file system access. This means developers can build experiences where users can install dependencies, run development servers, and execute code exactly as they would on their local machine, but entirely within a web page. The runtime supports all major frameworks and browsers, and it's significantly faster than local development environments for many operations.

This tool benefits companies building developer education platforms, documentation sites with live examples, and web-based coding environments. Teams at Google, Shopify, and Cloudflare use WebContainers to create interactive learning materials. Educational platforms like SvelteKit's tutorial system and Egghead.io embed WebContainers to let users practice coding without leaving their browsers. Developer tool companies can use it to demonstrate their APIs with working examples that users can modify and run immediately.