1. A method comprising: receiving, at data processing hardware, a first search query through a user device in communication with the data processing hardware; transmitting the first search query from the data processing hardware to a query analysis system and a first search system; receiving, at the data processing hardware, first search results from the first search system; receiving, at the data processing hardware, query information from the query analysis system, the query information comprising application programming interface information for an application programming interface of a second search system; transmitting a second search query from the data processing hardware to the application program interface of the second search system, the second search query based on the query information; receiving, at the data processing hardware, second search results from the second search system; determining, by the data processing hardware, a result set comprising at least some of the first search results and the second search results, at least one search result comprising an application access mechanism having a reference to a corresponding installed application on the user device and indicating a performable operation for the corresponding installed application; and displaying, by the data processing hardware, the results set in the user interface on the screen.