1. A computer-implemented method comprising: storing a plurality of application indexes, wherein each application index corresponds to one or more application categories of a plurality of application categories, wherein each application index comprises identifiers for a plurality of application representations, and wherein a subset of the application indexes are associated with a partner system; receiving a search query from a computing device associated with the partner system; identifying an application category based on the received search query, the application category indicating a platform executing on the computing device; selecting an index from the plurality of application indexes based on the identified application category and a partner identifier of the partner system; querying the selected index corresponding to the identified application category to identify a first plurality of application representations associated with the identified application category; identifying a second application category based on the received search query; selecting a second index from the plurality of application indexes based on the second identified application category and the partner identifier; querying the second index to identify a second plurality of application representations corresponding to the second application category; generating search results based on a union of the first plurality of application representations and the second plurality of application representations; and providing, for display, the generated search results to the computing device.