1. A method comprising: receiving, at data processing hardware, a first search query through a user device in communication with the data processing hardware in the user device; 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, the first search results being generated based on the first search query and query information generated in the query analysis system; receiving, at the data processing hardware, the 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; generating, at the data processing hardware, a second search query based on the query information; transmitting the second search query from the data processing hardware to the application programming interface of the second search system; 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 in the result set 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 result set in the user interface on screen.