Crowdsourcing serves as a distributed problem‐solving production model for modern governments, and it has the potential to transform citizens into coproducers of public services. To consolidate the theoretical basis, this article provides a typology for crowdsourcing public services based on theories of coproduction, public sector volunteerism, and government–citizen relations. This typology includes two dimensions—the policy stage, and the functionality of citizens' effort—and four types of crowdsourcing, namely, complementary crowdsourcing in service implementation, supplementary crowdsourcing in service implementation, complementary crowdsourcing in policy and service design, and supplementary crowdsourcing in policy design. Four cases are selected for illustration. Designing crowdsourcing based on citizen and government relationships will help designers align goals and tasks to the right coproducers and enhance relationships in a democratic way. Furthermore, this typology will allow the field to systematically and collectively build knowledge.