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.
Okta - Enterprise-grade identity management for all your apps, users & devices
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.
OneLogin - On-demand SSO, directory integration, user provisioning and more
Ping Identity - Ping Identity provides cloud-based, single sign-on and identity management solutions with their SAML SSO.