# Smart Biometric Login

One biometric every 7 days — save ReOTP costs

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## Overview
User logs in with biometric instead of sending WhatsApp every time, with periodic re-verification every 7 days.

### Implementation
1. "Login with Biometric" button using WebAuthn API.
2. On first success: call /api/verify/init (PREDICTIVE) to bind device.
3. Store credentialId + publicKey as TrustedDevice.
4. Within 7 days: verify WebAuthn only.
5. After 7 days: re-request ReOTP.

### UI/UX Guidelines
- Amber + zinc accents.
- Attractive biometric effects.

## Interactive Demo

Demo type: example
Example ID: usecase-9
Title: Interactive Live Preview

See the live demo at: https://reotp.com/bn/docs/usecase-9-smart-2fa-biometric