@Robert Chen checkout Factual. To my knowledge they have the most reliable data pool. They are the data provider though (they don't have their own DSP to buy media). You can buy audience data from them and have it uploaded to FB ads or a DSP for targeting (here's a list of partners: https://www.factual.com/company/partners/ ). Don't think you can upload their audiences to AdRoll (at least wasn't the case before). AdRoll does media buys with their so-called "algorithm" so you can't layer on additional 3rd party audience targeting. But doesn't hurt to ask your AdRoll account rep anyways.