YubiKey - The YubiKey is a one-time password device for secure login with two-factor authentication
X (Twitter) - Connect with your friends and other fascinating people. Get in-the-moment updates on the things that interest you. And watch events unfold, in real time, from every angle.
2FA Authenticator - Simple 2FA Authenticator - Generate Two Factor Authentication tokens.
Two Factor Auth (2FA) - List of websites and whether or not they support 2FA
U2F Zero - A secure and open source 2 factor authentication token. Designed to be affordable and reliable.
Google Titan - A 2FA device to protect yourself from hackers