CLOTP is a silly contraction of command-line OTP. OTP is an initialism of one-time password.
CLOTP is a one-time passcode generator with a couple of useful features. It stores the secret in the system's keystore and allows one to generate and copy to clipboard the two-factor authentication token.
I've written this as an investigation into how TOTP and HOTP work while writing a 2FA authenticator for Garmin watches (that project is now dead and abandoned and can be found on my GitHub).
One cool feature of this app is the ability to read the QR code generated by Google Authenticator and parse the exported keys.
Source code: GitHub