Browser Support

TryMellon uses WebAuthn Level 2. All major browsers support it.

Compatibility Matrix

Requirements

• HTTPS is required (except localhost for development)
• User gesture is required to trigger WebAuthn (click/tap)
• Conditional UI (autofill) requires autocomplete="username webauthn" on an input

Feature Detection

The SDK checks for WebAuthn support automatically:

const result = await client.authenticate({ externalUserId });
if (!result.ok && result.error.code === 'NOT_SUPPORTED') {
  // Browser doesn't support WebAuthn
  // Fall back to email OTP or show upgrade message
}

When WebAuthn is unavailable

Use the email OTP fallback. See Email Fallback.