OTP (plural OTPs)
- (cryptography) Initialism of one-time pad.
- (computing) Initialism of one time password: a password that is valid for only one login session or transaction.
- (fandom slang) Initialism of one true pair (or pairing): the romantic pairing preferred by an author or reader of fan fiction.
- (telecommunications) Initialism of Open Telecom Platform.
- (computing) Initialism of Opposite Track Path.
- (electronics) one-time programmable, for electronic devices that can only be programmed once.
- (instant messaging) On the phone.