Abstract: A method for verifying the identity of a user of an online service, with the steps of: when a user is connected (A1) to an online service (2), sending (A2) an IP address of an authentication server (3); connecting (B1) to said IP address and downloading one application (33) for taking photos with the webcam of the user terminal (1); taking a photo; sending (D2) said photo and associated metadata to a management unit (4); storing (E6) it in a data base (5); automatically extracting one set of biometrical parameters per each face which appears in said photo; comparing said set of biometrical parameters with a reference biometrical model of the user to which said user ID belongs; if the result of said comparison does not unequivocally match the person in the photo with the user to which said user ID belongs, either informing the web service provider (2) or sending (G1) said photo to a manual recognition unit (7) for manual validation of the photo; continuously verifying the identity of the user connected to the