Biometric Login

Use biometrics (Face ID / fingerprint) to let users log in without typing their credentials each time. The SDK can save, retrieve, and manage username/password pairs secured by biometric authentication.

Prerequisites

The starti.app SDK is installed and initialized
The device supports biometric authentication (Face ID or fingerprint)

Option A: Manual credential flow

Save and retrieve credentials directly with biometric protection.

Save credentials

await startiapp.Biometrics.setUsernameAndPassword("user@example.com", "s3cret");

Retrieve credentials

When retrieving, the user is prompted for biometric verification:

const credentials = await startiapp.Biometrics.getUsernameAndPassword(
  "Authenticate", // title shown in the biometric prompt
  "Log in to your account", // reason text
);

if (credentials) {
  console.log(credentials.username, credentials.password);
  // Use credentials to log in
} else {
  console.log("Biometric authentication failed or no saved credentials");
}

Check if credentials exist

const hasCreds = await startiapp.Biometrics.hasUsernameAndPassword();

Remove saved credentials

await startiapp.Biometrics.removeUsernameAndPassword();

Option B: Form-based auto-capture flow

Automatically capture credentials from a login form and prompt the user to save them.

await startiapp.Biometrics.startSaveUsernameAndPassword({
  usernameInputFieldSelector: "#email",
  passwordInputFieldSelector: "#password",
  submitButtonSelector: "#login-button",
  title: "Authenticate",
  reason: "Save your login for next time",
  language: "en", // or "da"
});

await startiapp.Biometrics.endSaveUsernameAndPassword();

The SDK intercepts the form submission, captures the entered credentials, asks the user if they want to use biometrics next time, and saves the credentials if they agree.

Checking biometric availability

const type = await startiapp.Biometrics.getAuthenticationType();
// Returns: "face" | "fingerprint" | "none"