A method and system for registering, storing and managing personal data for use over a network, and for allowing users to register for, link to and log onto third party Web sites. The invention queries a user for registration, authentication credentials information, such as user names, passwords, etc., for any type of application, and securely stores this data in a centralized user database. The invention prompts when registration/authentication is needed, and either manually with user intervention or automatically with user permission inputs stored data, or automatically creates the registration/authentication credential data for the user. The invention further monitors a user's network browsing, detects when registration/authentication is needed, and either manually with user intervention or automatically with user permission inputs stored data, or automatically creates the registration/authentication credential data for the user. The invention then securely transmits authentication credentials data for automatic login at third party Web sites.