Authy - Best rated Two-Factor Authentication smartphone app for consumers, simplest 2fa Rest API for developers and a strong authentication platform for the enterprise.
Aegis Authenticator - Aegis Authenticator is a free, secure and open source app to manage your 2-step verification tokens...
Google Authenticator - Google Authenticator is a multifactor app for mobile devices.
Microsoft Authenticator - One app to quickly and securely verify your identity online, for all of your accounts.
OTP Auth - The app for calculating one-time-passwords on iPhone and iPad.
YubiKey - The YubiKey is a one-time password device for secure login with two-factor authentication