Explore innovative techniques for leveraging advertising APIs to gather social media data for research purposes in this comprehensive conference talk. Discover how audience estimates from platforms like Facebook can be repurposed for remote social sensing and population mapping. Learn about projects utilizing this data to monitor international migration, map poverty, and track digital gender gaps. Gain insights into the opportunities and challenges of using audience estimates across various social media platforms, including Instagram, Snapchat, Twitter, LinkedIn, Google, and Weibo. Understand the methodological approach and its potential to complement existing data collection methods in social research. Delve into data visualizations, case studies, and discussions on the implications of using commercial data for academic and policy-oriented research.