I surely want to acknowledge my gratitude to this plugin's authors. Their work is to be measured by the effect it has on protecting WP sites and how effortlessly it works. Fricton-free and effective. Just great!
I really hate giving this one-star but the plugin is out of date and broken. This plugin was suggested to me back when I was looking for 2FA methods. It looked promising and worked great, but features are broken, it's fallen behind in supporting the latest versions of WordPress, and has not been updated in half a year. It's a real shame because I've not found a 2FA plugin that can match this plugin...
Really lightweight plugin, it seemed safe to implement and worked for day until admins reported issues. However, my case seems to be a conflict with Toolset Access and I am now having an impossible time trying to remove from my site. Even though I have deactivated, the combination of both these plugins seems to have corrupted the user access table. When an admin accesses the login page, we get a message "You don’t have permission to access this page." Sometimes, changing browsers/VPNs fixes it temporarily. There is no way to remove the plugin settings with uninstall.
This plugin is great for increasing login security by enabling Yubikey 2-Factor Authentication (FIDO U2F), or Time-based One Time Passwords (TOTP). It's very impressive; as if the Wordpress devs themselves integrated it. It even lets you create application-specific passwords (so you can log in with a password on the Wordpress app).