A compilation target for executing in a virtual machine supported by web browsers and servers (via tools like wasmtime). WebAssembly is intended to be portable between platforms and has a similar ‘write once run anywhere’ ethos as Java. WebAssembly already runs significantly faster than JavaScript in the browser and there is reason to believe the gap will widen as WebAssembly support improves.

Current limitations include by native access to manipulating the DOM, compiling from garbage collected languages results in huge binaries, and performance (Firefox is the fastest). Rust has the most mature support for compiling to wasm.

See also: