How does Google Authenticator work?
One really good TOTP app for desktops is Authy [0] from Twilio. Some people are not aware that it exists and you don't need an app on your phone for TOTP. Authy works from your desktop as well.<p>[0] <a href="https://authy.com/download/" rel="nofollow">https://authy.com/download/</a> (scroll down to see Desktop version for download)