This document summarizes a presentation on lean startup principles for mobile app development. It discusses how most apps get low download numbers and user engagement. It emphasizes building Minimum Viable Products (MVPs) and prototypes to test assumptions through user experiments and feedback, rather than fully developing apps without validation. Specific tips include using paper mockups and photos to quickly prototype apps; gathering blind user feedback; testing in different countries before major launches; and focusing on loops that drive user invite, content creation, and purchases. The document encourages questions and provides contact details.