1. A system, comprising: one or more computers; and a computer-readable device coupled to the one or more computers having instructions stored thereon which, when executed by the one or more computers, cause the one or more computers to perform operations comprising: receiving an initial index, the initial index associating each application of one or more applications with one or more applications of interest to provide one or more application pairs, each application pair associated with a weight that identifies a degree to which the applications of the application pair are related, the applications being executable on a mobile computing device; for each application, receiving scoring metadata associated with the application and receiving scoring metadata associated with each of the one or more applications of interest, the scoring metadata comprising title metadata, description metadata, and permission metadata, the permission metadata including data related to permissions by the application and the one or more applications of interest to access an application programming interface of the mobile computing device; for each application pair, comparing the scoring metadata associated with the application with the scoring metadata associated with the application of interest; based on the comparison, calculating, for each application pair, one or more similarity scores; calculating a metadata score based on the one or more similarity scores for each application pair; calculating an overall score for each application pair based on a combination of i) the metadata score associated with each application pair and ii) the weight associated with each application pair; and removing an application of interest of at least one application pair from the initial index when the overall score of the at least one application pair is less than a threshold score to provide a final index, the final index associating each application of the one or more applications with a remaining one or more applications of interest.