notp - Node One Time Password library, supports HOTP, TOTP and works with Google Authenticator
Simple to use, fast, and with zero dependencies. The Node One Time Password library is fully compliant with HOTP (counter based one time passwords) and TOTP (time based one time passwords). It can be used in conjunction with the Google Authenticator which has free apps for iOS, Android and BlackBerry. Google authenticator requires that keys be base32 encoded before being used. This includes manual entry into the app as well as preparing a QR code URI.