Expo Docs MCP Server

--- title: LocalAuthentication description: A library that provides functionality for implementing the Fingerprint API (Android) or FaceID and TouchID (iOS) to authenticate the user with a face or fingerprint scan. sourceCodeUrl: https://github.com/expo/expo/tree/sdk-52/packages/expo-local-authentication packageName: expo-local-authentication iconUrl: /static/images/packages/expo-local-authentication.png platforms: ["android", "ios"] --- import { ConfigReactNative, ConfigPluginExample, ConfigPluginProperties, } from '~/ui/components/ConfigSection'; `expo-local-authentication` allows you to use the Biometric Prompt (Android) or FaceID and TouchID (iOS) to authenticate the user with a fingerprint or face scan. ## Known limitation ### iOS&ensp; The FaceID authentication for iOS is not supported in Expo Go. You will need to create a [development build](/develop/development-builds/introduction/) to test FaceID. ## Installation ## Configuration in app config You can configure `expo-local-authentication` using its built-in [config plugin](/config-plugins/introduction/) if you use config plugins in your project ([EAS Build](/build/introduction) or `npx expo run:[android|ios]`). The plugin allows you to configure various properties that cannot be set at runtime and require building a new app binary to take effect. ```json app.json { "expo": { "plugins": [ [ "expo-local-authentication", { "faceIDPermission": "Allow $(PRODUCT_NAME) to use Face ID." } ] ] } } ``` If you're not using Continuous Native Generation ([CNG](/workflow/continuous-native-generation/)) or you're using a native **ios** project manually, then you need to add `NSFaceIDUsageDescription` key to your **ios/[app]/Info.plist**: ```xml Info.plist <key>NSFaceIDUsageDescription</key> <string>Allow $(PRODUCT_NAME) to use FaceID</string> ``` ## API ```js ``` ## Permissions ### Android The following permissions are added automatically through this library's **AndroidManifest.xml**: ### iOS The following usage description keys are used by this library: