Google Authenticator - Google Authenticator is a multifactor app for mobile devices.
Duo Security - Duo Security provides cloud-based two-factor authentication. Duo’s technology can be deployed to protect users, data, and applications from breaches, credential theft, and account takeover.
Authy - Best rated Two-Factor Authentication smartphone app for consumers, simplest 2fa Rest API for developers and a strong authentication platform for the enterprise.
Lastpass - LastPass is an online password manager and form filler that makes web browsing easier and more secure.
Protectimus - Protectimus ia a two-factor authentication solution.
Clef - Clef is secure two-factor with no passwords or tokens.