A method and apparatus for event attribution during software experimentation is described. The method may include receiving, by a server computer system, a plurality of event tracking messages associated with an end user system, each event tracking message including at least a customer identifier, an end user identifier, and a timestamp. The method may also include storing each event tracking messages with the received customer identifier, end user identifier, and timestamp in a customer data store. Furthermore, the method may include applying, by the server computer system, a feature treatment to a configurable application executing on the end user system, the feature treatment specified by a customer system associated with the customer identifier, and the feature treatment configures one or more features of the configurable application associated with the end user identifier. The method may also include attributing a first set of events from the received plurality of event tracking messages with the application of the feature treatment.