Local app development

Learn how to compile and build your app locally when using Expo.

To build your project into an app locally using your machine, you have to manually generate native code before testing the debug build or creating a production build for it to submit to the app store. There are two ways you can build your app locally. This guide provides a brief introduction to both methods and references to other guides that are necessary to create this workflow.

Prerequisites

To follow the steps described in this guide, see the instructions below on how to set your development environment.

export JAVA_HOME=/Library/Java/JavaVirtualMachines/zulu-17.jdk/Contents/Home

export JAVA_HOME=/Library/Java/JavaVirtualMachines/zulu-11.jdk/Contents/Home

Local app compilation

To build your project locally you can use compile commands from Expo CLI which generates the android and ios directories:

The above commands compile your project, using your locally installed Android SDK or Xcode, into a debug build of your app.

• These compilation commands initially run npx expo prebuild to generate native directories (android and ios) before building, if they do not exist yet. If they already exist, this will be skipped.
• You can also add the --device flag to select a device to run the app on — you can select a physically connected device or emulator/simulator.
• You can pass in --variant release (Android) or --configuration Release (iOS) to build a production version of your app.

To modify your project's configuration or native code after the first build, you will have to rebuild your project. Running npx expo prebuild again layers the changes on top of existing files. It may also produce different results after the build.

To avoid this, add native directories to the project's .gitignore and use npx expo prebuild --clean command. This ensures that the project is always managed, and the --clean flag will delete existing directories before regenerating them. You can use app config or create a config plugin to modify your project's configuration or code inside the native directories.

To learn more about how compilation and prebuild works, see the following guides:

Local builds with expo-dev-client

If you install expo-dev-client to your project, then a debug build of your project will include the expo-dev-client UI and tooling, and we call these development builds.

To create a development build, you can use local app compilation commands (npx expo run:[android|ios]) which will create a debug build and start the development server.

Local builds with EAS