Embodiments of the present invention provide a method and system for de-anonymization of online user identity, user tracking techniques, user behavior and preference analysis, customization of user interfaces, and combinations thereof. Fingerprinting attributes may be collected from a client device during anonymous browsing to identify the user, and based on tracked activities from the browsing session, a user profile for that user may be created and/or updated. When a user using the client device with the same fingerprinting attributes initiates a login session, the information from the stored user profile may be used to create a customized user interface.