WebAssembly

WebAssembly (Wasm) is rarely written by hand. Compilers turn Rust, C, C++, Go, Kotlin, C# and other languages into a .wasm file, which the browser loads, checks and runs inside the same security sandbox as JavaScript. It became a W3C standard in 2019 and runs in every major browser.

It suits heavy, well-defined work: image and video editing, games, CAD, codecs and encryption, or bringing an existing C++ library to the web; Figma and Photoshop on the web rely on it. Wasm cannot touch the page directly, so it works alongside JavaScript, which handles the DOM. Outside the browser, WASI and runtimes such as Wasmtime run Wasm modules on servers, and edge platforms such as Cloudflare Workers can run them too.