This chapter introduces open digital innovation contests that aim to develop digital services. Key stakeholders in such contests are identified: organisers, participants, resource providers, and beneficiaries. A classification of digital innovation contests is proposed based on the length of a contest and its inclusiveness in terms of participants. Other design elements of contests are also discussed, including media, target group, and evaluation. It is argued that innovation contests can be viewed as innovation intermediaries that help to connect actors in an innovation system. Advantages and disadvantages of innovation contests are discussed. Finally, 11 contests are introduced, which serve as running examples throughout the book.