Running WASM in React Native apps

Kræn Hansen - MongoDB / Robert Pasiński - Callstack

As building cross-platform mobile and desktop apps in React Native (OSS by Meta) is ever increasing. As the ecosystem is closing the gap towards Web-APIs, it is increasingly feasible to build performant and truly universal apps and libraries. The latest advancement is the ability to execute WASM in a React Native app.

In this talk, I’ll start from my naive approach of implementing a native module for React Native, exposing the Wasmer runtime, which turned out to be really slow, mainly because of the restriction on iOS devices that apps are not allowed to perform just-in-time compilation on devices. This however is balanced with the React Native platform’s ability to run ahead-of-time compiled native code and the current solution, built and maintained by Callstack, uses wasm2c to build native modules for React Native.