With the proliferation of digital technologies, multi-sided platforms become a prevailing choice of asset-light business model in facilitating business transactions. As of 2023, Uber’s market value stands at $90 billion while Airbnb’s market valuation is $100 billion. Neither of them owns the vehicles or the properties. Coordinating users, launching products, and designing rules are challenging for platform managers, especially when they do not fully control either supply or demand side of the marketplace. This dissertation examines three unique interactions of platform users: bypassing the platform, pooling riders in a vehicle, and teaming up donors within a group. Chapter 2 studies disintermediation and its mitigation policies on a home-sharing marketplace. Chapter 3 investigates the impacts of extending product line by introducing carpooling services on a ride-sharing platform. Chapter 4 examines the effects of subteaming on incentivizing donations on an online charity platform. My dissertation applies a variety of empirical methods to highly granular data, and offer implications for platform stakeholders in feature designs, product strategy and platform governance.