YouTube has launched a Creator Partnerships API that gives brands access to performance data on audience engagement and viewership. Read past the announcement language and what it does is convert creator deals from a relationship business into a media planning exercise that looks like buying any other inventory. That’s a bigger change than it sounds, and creators should think carefully about which side of it they end up on. What the API replaces Influencer marketing has run for a decade on a mix of screenshots, agency relationships, negotiated rate cards and trust.