[Home](./index.md) > [@firebase/app](./app.md) ## app package Firebase App ## Remarks This package coordinates the communication between the different Firebase components ## Functions | Function | Description | | --- | --- | | [deleteApp(app)](./app.deleteapp.md) | Renders this app unusable and frees the resources of all associated services. | | [getApp(name)](./app.getapp.md) | Retrieves a FirebaseApp instance.When called with no arguments, the default app is returned. When an app name is provided, the app corresponding to that name is returned.An exception is thrown if the app being retrieved has not yet been initialized. | | [getApps()](./app.getapps.md) | A (read-only) array of all initialized apps. | | [initializeApp(options, name)](./app.initializeapp.md) | Creates and initializes a FirebaseApp instance.See [Add Firebase to your app](https://firebase.google.com/docs/web/setup#add_firebase_to_your_app) and [Initialize multiple projects](https://firebase.google.com/docs/web/setup#multiple-projects) for detailed documentation. | | [initializeApp(options, config)](./app.initializeapp_1.md) | Creates and initializes a FirebaseApp instance. | | [onLog(logCallback, options)](./app.onlog.md) | Sets log handler for all Firebase SDKs. | | [registerVersion(libraryKeyOrName, version, variant)](./app.registerversion.md) | Registers a library's name and version for platform logging purposes. | | [setLogLevel(logLevel)](./app.setloglevel.md) | Sets log level for all Firebase SDKs.All of the log types above the current log level are captured (i.e. if you set the log level to info, errors are logged, but debug and verbose logs are not). | ## Interfaces | Interface | Description | | --- | --- | | [FirebaseApp](./app.firebaseapp.md) | A FirebaseApp holds the initialization information for a collection of services.Do not call this constructor directly. Instead, use [initializeApp()](./app.initializeapp.md) to create an app. | | [FirebaseAppConfig](./app.firebaseappconfig.md) | Configuration options given to [initializeApp()](./app.initializeapp.md) | | [FirebaseOptions](./app.firebaseoptions.md) | Firebase configuration object | ## Variables | Variable | Description | | --- | --- | | [SDK\_VERSION](./app.sdk_version.md) | The current SDK version. |