Recently I had to suggest a 2 factor authentication applicative for Windows. Of course I searched on alternativeto.net for a free-as-in-freedom program running on Windows founding this:

2fast (acronym for two factor authenticator supporting TOTP) is a free, open source, two factor authenticator for Windows and other platforms. 2fast has the ability to store the encrypted data at a place of your choice instead of a 3rd party cloud location.

They tried it and I can say it is well designed

Let’s hope that their IT departement will never enable TOTP for log in their desktops, otherwise they may be locked out. I suggested to save the QR-Code seed elsewhere.