1. An application optimization system, comprising: a plurality of client devices transmitting user application interaction data to at least one server; at least one hardware server processing the user application interaction data into descriptive data including the user application interaction data and relations between the user application interaction data, wherein the relations are based on at least one of user properties, time, application interaction, transactions, transaction properties, interaction properties, and corresponding relationships between them, the at least one server comprising non-transitory computer-readable media embodying computer-readable instructions operable to cause one or more processors to perform a method for optimizing an application, the method including: receiving, via a server comprising a processor circuit, a request for a tuning variable configured to control behavior of an application; analyzing, via the server, the request, including determining whether the requested tuning variable is assigned to an active experiment; assigning, via the server, a value to the tuning variable based on the analyzing, the assigning comprising: when the requested tuning variable is assigned to an active experiment, determining whether an entity associated with the request is assigned to the active experiment and/or qualified for the active experiment; when the entity associated with the request is assigned to the active experiment and/or qualified for the active experiment, assigning a value associated with the active experiment to the tuning variable; and when the entity associated with the request is not assigned to the active experiment and/or qualified for the active experiment, assigning a default value to the tuning variable; and sending, via the server, the tuning variable.