How OpenAI Builds for 800 Million Weekly Active Users: Model Specialization and Fine-Tuning We sat down with Sherwin Wu, Head of Engineering at OpenAI Platform, to discuss OpenAI’s developer strategy, how to manage top ML teams, why they decided to start releasing open-weight models again, how prompt engineering has evolved over time, and how developer tools will shift to accommodate better agents moving forward. 00:00 Introduction 8:36 Horizontal vs vertical OpenAI 12:18 Why you can’t “disintermediate” the model 15:11 People build relationships with models 17:30 Not one AGI model but many 20:10 Fine-tuning, RFT, and customer data choices 24:44 Prompt engineering isn’t the point anymore 28:06 What an “agent” really is 31:55 How OpenAI thinks about pricing 36:46 Why open-weights don’t kill the API 42:57 Different stacks for text, images, video 45:47 How the agent builder actually works @sherwinwu @martin_casado(a16z)