A common economic process is crowdsearch, wherein a group of agents is invited to search for a valuable physical or virtual object, e.g. creating and patenting an invention, solving an open scientific problem, or identifying vulnerabilities in software. We study a binary model of crowdsearch in which agents have different abilities to find the object. We characterize the types of equilibria and identify which type of crowd maximizes the likelihood of finding the object. Sometimes, however, an unlimited crowd is not sufficient to guarantee that the object is found. It even can happen that inviting more agents lowers the probability of finding the object. We characterize the optimal prize and show that offering only one prize (winner-takes-all) maximizes the probability of finding the object but is not necessarily optimal for the crowdsearch designer.
