1. A method, comprising: subscribing, with an outsourcing provider system, a first client and a second client; linking, by a platform running on an outsourcing provider computer system, first application functionality provided by a first application provider computer system with a first tenant instance corresponding to the first client and second application functionality provided by a second application provider computer system with a second tenant instance corresponding to the second client, wherein the first and second tenant instances have first and second defined configurations of services individually subscribed to by the first and second clients, respectively, and the platform on the outsourcing provider computer system performs an outsourced function from each of the first application functionality and the second application functionality provided by the first and second application provider computer systems, respectively; accessing aggregate data from the first and second tenant instances needed to perform the outsourced function, using the aggregate data to perform outsourcing services for the first and second clients, respectively, without requiring host software associated with the platform to be used by any of the first and second clients and the first and second tenant instances; determining, by the platform, that a first event has occurred within the first tenant instance and a second event has occurred within the second tenant instance; receiving, by the platform, first data from the first tenant instance and second data from the second tenant instance; processing, by the platform, the first event using the first data, the first defined configuration of services, and the outsourced function of the first application functionality to obtain a first result, and processing the second event using the second data, the second defined configuration of services, and the outsourced function of the second application functionality to obtain a second result; and performing, by the platform, first and second outsourced actions based on the first and second result.