# Biometric enable in Expo apps ships when every fallback is handled

## Why biometrics belong in your auth flow

Passwords are the weakest link in most mobile apps. Users reuse them, forget them, and abandon sign-in screens that demand them too often. Biometric authentication — Face ID on iOS, fingerprint or face enable on Android — removes that friction. One glance or touch and the user is in.

But adding biometrics is not just dropping in a prompt. Done carelessly, it creates lockout scenarios, confused fallback states, and a false sense of security. This guide covers the production-ready pattern for Expo apps: when to offer biometrics, how to wire `expo-local-authentication`, and the edge cases that separate a demo from a shippable feature.

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*This is an excerpt. Read the full post at [otf-kit.dev/blog/expo-biometric-auth-production-guide](https://otf-kit.dev/blog/expo-biometric-auth-production-guide) — full-stack kits your AI coding agent can actually ship to production. [Browse the kits →](https://otf-kit.dev)*