Reddit’s mission is to bring community and belonging to every person in the world. A huge part of fulfilling this is helping users find the communities they love and surfacing the most relevant conversations. In this talk we will explore how Reddit has taken a “platform first” approach to scaling recommendation and personalization via its Ranking Platform. We will take a look at where this platform sits within Reddit’s tech stack and the strategic value that it adds. Then we will dive deeper into the Ranking Platform architecture and how machine learning engineers and software engineers can collaborate to develop recommendation and personalization experiences for Redditors.