Learn why your React Native app’s bundle size matters & how tools like Expo Atlas help you optimize performance, reduce app startup time & improve dependency management.

Callstack Blog

Bundle size in React Native apps still affects startup time and memory footprint even with Hermes ahead-of-time compilation, and becomes critical for OTA updates, iOS App Clips, and Android Instant Apps. Expo Atlas is a bundle analysis tool that hooks into Metro's dependency graph to give a complete, module-by-module breakdown of what contributes to bundle size. Unlike Source Map Explorer, it resolves unmapped regions (up to 30% of bundle size) caused by Babel plugins. Setup in Expo projects is a single environment variable; vanilla React Native projects can use the `expo-atlas-without-expo` package to get the same functionality without adopting the full Expo framework.

Why Your React Native App’s Bundle Size Matters and How Expo Atlas Helps

How does Expo Atlas compare to similar tools?

Using Expo Atlas with vanilla React Native