Published: Oct 28, 2020
Oct 2020

Hermes is a JavaScript engine optimized for fast start-up of React Native applications on Android. JavaScript engines such as V8 have just-in-time (JIT) compilers that profile the code at run time to produce optimized instructions. Hermes, however, takes a different approach by compiling the JavaScript code ahead of time (AOT) into an optimized bytecode. As a result you get a smaller APK image size, lean memory consumption and faster startup time. We're carefully assessing Hermes in a few React Native apps and recommend you do the same.