This book chapter examines how AI-driven prototyping is transforming startup product development by enabling non-technical founders of startups to build functional digital products rapidly and independently. Tracing the shift from traditional coding to no-code tools and Generative AI, the chapter highlights the strategic advantages of speed and accessibility while cautioning against risks related to scalability and maintainability. Moreover, the chapter also concludes that AI reshapes, but does not replace, the role of developers, positioning them as architects of sustainable systems in a new, leaner startup model.