Passkey
A passkey is a credential stored on the device that replaces a password, unlocked with Face ID, a fingerprint or a screen lock. People give only a user name, and nothing typed can be phished.
Why it matters
Passwords are what people forget and what leaks. A passkey removes both, and the sign-in becomes one biometric check.
It is a system dialog, so the design owns the screens around it: the offer, the wording of the button and the fallback.
Passkey on iOS and Android
Also called Passwordless sign-in, Credential Manager, Biometric sign-in. The same idea in each system, with the values Appetite UI gives it.
| Value | iOS | Android | Appetite UI |
|---|---|---|---|
| Name | Passkeys, sign in with Face ID or Touch ID | Credential Manager with passkeys | Passkey |
| Flows in the file | Create, Sign In, Cross-Device, Security Key | Same flows, drawn as the iOS dialog | See below |
| Platform support | Preferred by Apple when Sign in with Apple is not used | Android 9 (API level 28) and higher | See below |
In Appetite UI
Passkey is a dialog set on the Alert page: four flows, Create, Sign In, Cross-Device and Security Key, each in three states, Prompt, Verifying with a Face ID glyph, and Success. It shares the Alert card, a primary action in the tint and secondary actions on flat capsules.
Example
After a person creates an account, a Create dialog offers to save a passkey. Next time the Sign In dialog asks for Face ID and the app opens without a password field.
Common mistakes
- Titling a button Sign In when it means Sign In with Face ID. Name the method.
- Mentioning Face ID on a device that does not have it.
- Removing the password fallback before people have passkeys.
- An in-app setting for biometrics, which people already set in the system.
Questions
What is a passkey?
A credential stored on the device that replaces a password. People confirm with a biometric or screen lock, and it uses public-key cryptography, so a breach of the service does not expose it.
Do passkeys work across iOS and Android?
Yes. Android Developers lists support for Android, Windows, macOS and iOS, and several browsers, with passkeys on Android 9 and higher.
Sources
The pages the facts above rest on, each read October 30, 2026.