A few years ago, Mozilla Labs was prototyping a client-side API called "User Personalization" for users to express their interests or purchasing intent: https:

A few years ago, Mozilla Labs was prototyping a client-side API called "User Personalization" for users to express their interests or purchasing intent: https://blog.mozilla.org/labs/2013/07/a-user-personalization-proposal-for-firefox/ https://blog.mozilla.org/labs/2013/07/a-user-personalization...