Abstract: Systems and methods to store, exchange, and aggregate data in association tokens representative of personally identifiable information (PII) without revealing the PII to users of the data. The PII is secured in a centralized location for association with the tokens but without the associated data. Data records are stored in data sources in association with tokens representing the PII but without the PII. Before providing a set of data records from the data sources to a user, a master token is identified based on the data stored in the centralized location to represent a plurality of tokens used in the data records to represent a same person/entity; and the plurality of tokens are replaced with the master token for the data records to link together the data records of the same person/entity.