OTP Generator
Generate Time-based One-Time Passwords (TOTP) for two-factor authentication.
About TOTP
Time-based One-Time Password (TOTP) is a standard algorithm for generating temporary codes used in two-factor authentication.
The codes change every 30 seconds (by default) and are derived from a shared secret key using HMAC-SHA1.
This implementation follows RFC 6238 and is compatible with Google Authenticator, Authy, and similar apps.