Embodiments facilitate confidential and secure sharing of anonymous user profile data to improve the delivery of customized content. Embodiments of the invention provide a data appliance to an entity such as a business to convert profile data about the business's customers into anonymous identifiers. A similar data appliance is provided to a content provider in one embodiment to generate identifiers for its user profile data. Because the anonymous identifiers are generated with the same anonymization method, identical identifiers are likely generated from profile data of the same users. Therefore, the identifiers can be used to anonymously match the customers of the business to the users of the content provider. Therefore, data can be shared to improve customized content such as advertisements that the business wishes to place with the content provider without requiring the business to disclose customer data in an unencrypted form, and any non-matched data can remain confidential.