[Home](./index.md) > [@firebase/auth](./auth.md) > [getAuth](./auth.getauth.md) ## getAuth() function Initializes an Auth instance with platform specific default dependencies. Signature: ```typescript export declare function getAuth(app?: FirebaseApp): Auth; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | app | [FirebaseApp](./app.firebaseapp.md) | The Firebase App. | Returns: [Auth](./auth.auth.md)