# Set up authentication using a Custom Token

## Android

1. See [Before you begin](https://firebase.google.com/docs/auth/android/custom-auth#before-you-begin) and follow the instructions to configure sign-in with Custom Token correctly.  
   **Attention**: Skip step 2. The dependency for the Firebase Authentication Android library is already declared by the plugin.

## iOS

1. See [Before you begin](https://firebase.google.com/docs/auth/ios/custom-auth#before-you-begin) and follow the instructions to configure and enable sign-in with Custom Token correctly.  
   **Attention**: Skip step 2. The `FirebaseAuth` pod is already added by the plugin.

## Web

1. See [Before you begin](https://firebase.google.com/docs/auth/web/custom-auth#before-you-begin) and follow the instructions to configure and enable sign-in with Custom Token correctly.
