> ## Documentation Index
> Fetch the complete documentation index at: https://docs.corbado.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Passkey Login: Identifier-First

> Identifier-first flow where users enter their username/email and the system uses Passkey Intelligence to automatically determine the optimal authentication method.

## Identifier-First Login

This is an **identifier-first flow** where users enter their identifier (email, phone, or username) into the login textfield first. The system then uses **[Passkey Intelligence](/corbado-connect/features/passkey-intelligence)** to automatically determine if passkey login should be triggered on the current device or via cross-device authentication.

**Critical for Login Success:** Passkey Intelligence only triggers platform or cross-device login when there's a high probability of success. This smart decision-making significantly increases overall login completion rates by avoiding failed authentication attempts.

<Info>
  **How Passkey Intelligence Works:** After the user enters their identifier, the system uses [Passkey Intelligence](/corbado-connect/features/passkey-intelligence) to make smart decisions about authentication. It only triggers platform authentication or cross-device login when there's a high likelihood of success. This prevents users from encountering failed authentication attempts, which significantly improves overall login completion rates.
</Info>

<Info>
  **Configuration Options:** This flow can be configured in different ways based on your requirements:

  * **Option 1: `preferImmediatelyAvailableCredentials`** - Restricts to immediately available passkeys on this device. When the user enters their identifier, this configuration filters the displayed passkeys to only show those matching the entered identifier, providing a streamlined experience.

  * **Option 2: Full support** - Allows security keys and cross-device authentication (CDA). Security key support may be desired for certain use cases, while CDA is less commonly used on native apps.

  [Passkey Intelligence](/corbado-connect/features/passkey-intelligence) helps determine which configuration is optimal for your use case. Contact us for implementation guidance on advanced configurations.
</Info>

<Tabs>
  <Tab title="iOS" />

  <Tab title="Android" />
</Tabs>

<Steps>
  <Step title="User enters identifier">
    * User types their identifier (email, phone, or username) into the login textfield in the native app.
    * System now knows which user account is attempting to log in.
  </Step>

  <Step title="Passkey Intelligence determines authentication method">
    * The system uses [Passkey Intelligence](/corbado-connect/features/passkey-intelligence) to analyze if this user has a passkey available.
    * It intelligently determines the best authentication approach:
      * **Platform authentication:** If a passkey is stored on the current device
      * **Cross-device authentication:** If a passkey exists on a mobile device
      * **Fallback to traditional login:** If no viable passkey route is detected
    * **Key advantage:** Only triggers passkey login if there's a high probability of success, preventing user frustration from failed attempts.
  </Step>

  <Step title="OS-native passkey prompt appears">
    * If Passkey Intelligence determines a passkey is available, the system automatically triggers the authentication prompt.
  </Step>

  <Step title="Biometric authentication prompt appears">
    * User verifies their identity using the device's screen lock (fingerprint, PIN, or face recognition).
    * Upon successful verification, the user is seamlessly logged in.
  </Step>
</Steps>