A new tutorial demonstrates how to compile and run C code as WebAssembly entirely within a web browser—no local tools or installations needed. The approach uses GitHub Codespaces as a cloud-based development environment and Emscripten to compile C code into WASM modules that execute at near-native speed directly in the browser.

The step-by-step guide covers creating a minimal "Hello WASM!" application by launching an online Visual Studio Code instance via Codespaces, writing C code in the browser, compiling it with Emscripten, and running a Python HTTP server to serve the generated web app. This workflow removes traditional barriers like environment setup, dependency conflicts, and OS limitations.

WebAssembly transforms browsers from presentation layers into computational platforms capable of running performance-critical code originally written in C, C++, or Rust. The author built this tutorial while developing a platform for in-browser molecular structure analysis, where existing scientific libraries in C needed WASM ports to run without user installations.