This chapter explores how open digital innovation can be activated and extended through structured engagement with external developers and innovators. We begin by analysing the characteristics of innovation in digital innovation contests, such as hackathons and innovation challenges. Through two case studies, we illustrate how these contests stimulate early-stage prototyping and problem-solving. We then identify key actions organisers can take to foster innovation during such events. Building on these insights, we expand the scope of what open digital innovation contests can be—both in terms of inputs and expected outcomes. We also explore how open digital innovation contests can act as a learning platform supporting educational initiatives. Finally, we introduce how open digital innovation can also be managed through other innovation models besides contests. These include innovation garages, business accelerators, and venture hubs, which support innovation in different stages of maturity.