What is the difference between Expo Go and a custom development build?

These two development options differ in what native capabilities they support: Expo Go: a pre-built app downloaded from the App Store/Play Store. Contains a fixed set of pre-compiled native modules (the Expo SDK). You point it at your Metro bundler and run your JS code inside Expo Go. Pros: instant setup (no Xcode/Android Studio needed), fast to start, works on physical devices easily. Cons: limited to Expo SDK's built-in modules — can't use custom native modules or third-party packages with native code not in the SDK. Custom Development Build (using EAS Build): a development version of YOUR app with your own native code. Built using eas build --profile development. Supports any native module (react-native-vision-camera, react-native-ble-plx, custom modules, etc.). Includes Expo Dev Client — same DX as Expo Go but with your native code. Pros: full native access, installable as a real app, same workflow as production build. Cons: requires initial build time (~10-20 minutes), needs EAS account (or local build). When to use each: Expo Go — learning, prototyping, apps that don't need custom native code; Development Build — production apps, when you need any native library not in Expo SDK, when you're beyond the prototype phase. Development profile in eas.json: { "build": { "development": { "developmentClient": true, "distribution": "internal" } } }. Most production Expo apps: use custom development builds. Expo Go is primarily for learning and rapid prototyping.