What is the difference between name and slug?

name is the human-readable display name of your app, while slug is a URL-friendly identifier used by Expo and EAS to reference the project. The slug should be lowercase with hyphens and stay stable across builds.

Where do iOS and Android specific settings go?

Platform-specific settings live under the ios and android objects. For example ios.bundleIdentifier sets the iOS bundle ID and android.package sets the Android application ID; both are required for production builds and store submission.

Should I use app.json or app.config.js?

Use app.json for static configuration. Switch to app.config.js (or .ts) when you need dynamic values, such as reading environment variables or changing the bundle ID per build profile, because it is evaluated as JavaScript at build time.

What is runtimeVersion for?

runtimeVersion identifies the native runtime an over-the-air update is compatible with. EAS Update only delivers a JS bundle to apps with a matching runtimeVersion, preventing an update from running against incompatible native code.

How do I set Info.plist keys or Android permissions from Expo?

Use ios.infoPlist for raw Info.plist entries and android.permissions for the manifest permission list, or attach a config plugin. These let you configure native settings without leaving managed Expo or ejecting.

Expo app.json Config Reference

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Expo app.json configuration

Expo apps are configured by an app.json file (or a dynamic app.config.js) whose expo object drives the build, store metadata and native settings. Some fields are shared across platforms; others live under ios, android or web. This searchable reference lists the key fields with their platform scope and type so you can configure builds and submissions correctly.

How it works

Static config lives under the top-level expo key:

{
  "expo": {
    "name": "Gera Warranty",
    "slug": "gera-warranty",
    "version": "2.1.0",
    "icon": "./assets/icon.png",
    "ios": { "bundleIdentifier": "com.gera.warranty", "buildNumber": "57" },
    "android": { "package": "com.gera.warranty", "versionCode": 57 },
    "runtimeVersion": { "policy": "appVersion" }
  }
}

For dynamic values, export from app.config.js instead and read process.env. EAS uses slug plus ios.bundleIdentifier / android.package to identify and submit the app, and runtimeVersion to gate OTA updates.

Tips and notes

Keep slug stable; changing it points EAS at a different project.
Bump ios.buildNumber and android.versionCode on every store upload.
Use runtimeVersion so OTA updates only reach compatible native builds.
Set native bits via ios.infoPlist, android.permissions or config plugins.