A system for aggregating a user's web browsing data which may include cookies placed on a user's computing device from various websites. The system receives authorization from a user to retrieve cookie and other data associated with the user. The system then accesses cookie data and personal data associated with the user. In some embodiments, the aggregation system communicates with websites that placed the cookie data on the user's computer to determine one or more characteristics of the user based on the cookie data (which may be understandable only by the placing website). The system may then provide the user's aggregated data or a portion thereof to requesting entities. The user may have access to a user interface which provides information about the user's aggregated data and allows the user to determine how much information to share with requesting entities.