1. A system comprising: a universal tag configuration subsystem comprising: a console server operable to configure universal tags, each universal tag including a data contract definition for: specifying data events and corresponding event data to collect from a designated website accessed by a user at a user device, and specifying client-defined transformation rules and taxonomy rules for interpreting the collected event data to generate a user profile corresponding to the user, the user profile including key-value pairs and categorizations; wherein the data contract definition is stored as a corresponding updated data contract in a database; and a listening server operable to: identify the updated data contract in the database, and generate runtime code instructions based on the updated data contract; and a runtime subsystem comprising: a profile server for storing the user profile; and a presentation server operable to: receive the runtime code from the listening server to instantiate a runtime endpoint, collect, at runtime, event data from the designated website, the event data specified by the data contract definition, apply the transformations to the collected event data, categorize the transformed event data based on the applied taxonomy rules, and store the transformed event data in the corresponding user profile at the profile server; wherein collecting event data includes providing a universal tag script, via the presentation server, for running in the context of the designated website to instantiate a universal tag to: collect event data from the designated website, and report the collected event data to the runtime endpoint for applying the transformation and taxonomy rules; and wherein applying the transformations to the collected event data includes performing an iterative loop via the runtime endpoint on the presentation server, the iterative loop comprising: automatically determining, via a data provider servlet application, a list of runtime transformation applications corresponding to data contracts corresponding to a particular provider ID; performing, via a runtime transform application, the appropriate transformations on event-value pairs; and for each event-value pair, return a key-value pair and appropriate category identification for storage at a runtime user profile application.