# Android

## Complete Guides

#### **Sign in with Device**

Allow users to login automatically from a device that they trust.

{% content-ref url="android/older-sdk-version/android-sdk" %}
[android-sdk](https://docs.cotter.app/sdk-reference/android/older-sdk-version/android-sdk)
{% endcontent-ref %}

#### Sign in with Email/Phone Number

Authenticate users by sending a Magic Link or OTP via email, SMS, or WhatsApp.

{% content-ref url="android/android-sdk-1" %}
[android-sdk-1](https://docs.cotter.app/sdk-reference/android/android-sdk-1)
{% endcontent-ref %}

#### Add Biometric/Pin

Add a second layer to protect your mobile app using Biometric or Pin.

{% content-ref url="android/android-sdk-2" %}
[android-sdk-2](https://docs.cotter.app/sdk-reference/android/android-sdk-2)
{% endcontent-ref %}