Web Authentication Immediate UI mode

at a glance

why it exists

The existing mediation: "conditional" flow shows passkey suggestions in the browser's native autofill UI — good for sign-in forms with a username field. But some flows (single-button sign-in, checkout, re-authentication) have no username field; they just need an immediate credential picker. uiMode: "immediate" triggers that picker directly on a user gesture, succeeds only when a credential exists, and fails fast when none does — so the site can fall back to a registration flow without showing a confusing empty dialog.

shape of the API

A single new option on the existing navigator.credentials.get() call:

Capability detection

Before using immediate mode, check that the browser supports it:

const caps = await PublicKeyCredential.getClientCapabilities();
if (caps.immediateGet) {
  // Safe to use uiMode: 'immediate'
}

example

One-click sign-in with passkey

signInBtn.addEventListener('click', async () => {
  const caps = await PublicKeyCredential.getClientCapabilities();
  if (!caps?.immediateGet) {
    // Fall back to conditional UI or form-based flow
    return startConditionalUI();
  }

  try {
    const credential = await navigator.credentials.get({
      uiMode: 'immediate',
      publicKey: {
        challenge: await fetchChallengeFromServer(),
        rpId: location.hostname,
        userVerification: 'required'
      }
    });
    // credential is a PublicKeyCredential; send to server to verify
    await verifyOnServer(credential);
  } catch (err) {
    if (err.name === 'NotAllowedError') {
      // No passkey available — offer registration
      startRegistrationFlow();
    } else {
      throw err;
    }
  }
});

Password credential support

const credential = await navigator.credentials.get({
  uiMode: 'immediate',
  password: true  // also accept saved passwords
});

browser support

see also

• MDN: CredentialsContainer.get() — full API reference
• WebAuthn Level 3 spec
• chromestatus — Web Authentication Immediate UI mode (5164322780872704)
• chrome-platform-showcase — live demo