What is WebAssembly (Wasm)?

What is WebAssembly (Wasm)?

WebAssembly, or Wasm, is a binary instruction format that runs code compiled from higher-level languages inside a safe sandbox in browsers and some server or edge runtimes. It is not meant to replace JavaScript entirely; it is used to run compute-heavy parts of an application in a portable way.

A Wasm module is often compiled from Rust, C, C++, or Go. In the browser, it usually runs alongside JavaScript. JavaScript handles DOM, network, and UI work, while Wasm can handle image processing, compression, encryption, game logic, or data processing.

Where It Is Used

Wasm is used in browser-based design tools, CAD viewers, video and audio processing, cryptographic operations, games, and scientific computing interfaces. In edge computing, some platforms use Wasm as a small, isolated, fast-starting plugin or function model; Cloudflare Workers is one of the environments where this topic often appears.

Wasm does not make every application faster. Access to many browser APIs still goes through a JavaScript bridge, and crossing that boundary has a cost. The best candidates are CPU-heavy units with limited input and output rather than UI code that constantly interacts with the DOM.