HubSpot moved from an application-focused company to a platform company by building an app marketplace. They saw marketing transition from an outbound push model to an inbound pull model, and their own tools fragmented across different vendors. Their solution was to create an integrated platform and open their APIs, allowing partners and customers to build apps. They released over 40 apps in 4 months, seeing rapid growth in installed apps. To successfully build an app marketplace, HubSpot focused on good customer experience, compelling incentives for developers, strong developer support, and internal commitment to APIs.