A One-Time Password (OTP) is a dynamic password used once in conjunction with an account's usual password, a for the purpose of two-factor authentication.
It can be based on a counter (HOTP) or a timestamp (TOTP). This module provides both methods.
Mobile authenticator applications will typically require a TOTP secret. They are most commonly provided as QR codes to scan. This library can generate a URI that can be used by a QR Code generator.