Okta - Enterprise-grade identity management for all your apps, users & devices
andOTP - andOTP is a two-factor authentication App for Android 4.4+
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.
Aegis Authenticator - Aegis Authenticator is a free, secure and open source app to manage your 2-step verification tokens...
OneLogin - On-demand SSO, directory integration, user provisioning and more
Authenticator - Authenticator is a simple, free, and open source two-factor authentication app.