systems and methods for multi - factor user authentication techniques usable in transactions . in some embodiments , an authentication platform receives a request to authenticate a user in conjunction with an online transaction and determines an authentication rule . the authentication platform then transmits an authentication request to the user &# 39 ; s mobile device , receives authentication response data from the user mobile device , and authenticates the user in conjunction with the transaction when the authentication response data matches stored user authentication data . an authentication message is then transmitted to the user &# 39 ; s mobile device . in some embodiments , the authentication response data is biometric data of the user obtained from at least one authenticator of the user &# 39 ; s mobile device .