6. A system for configuring a data contract definition for universal tag collection using a graphical user interface, comprising: a universal tag configuration subsystem comprising: a console server operable to: generate the graphical user interface for creating and managing the universal tags; display the graphical user interface at a client machine; and receive via the graphical user interface: a selection of a data provider with universal tag availability, and one or more of a plurality of domain names; and an event inspector tool for generating an event inspector panel on the graphical user interface in response to receiving the selection of the one or more domain names, wherein the event inspector tool is configured to receive data contract definitions, each data contract definition specifying: events and corresponding event data to collect from a designated website accessed by a plurality of end users at corresponding end user devices, and transformation rules and taxonomy rules for interpreting the collected event data to generate end user profiles corresponding to the plurality of end users, the end user profiles including key-value pairs and categorizations; wherein the event inspector tool receives event data contract definitions by: receiving a selection of an event bookmarklet to store onto a bookmark bar of a designated website corresponding to the one or more domain names; receiving a URL corresponding to a first page of the designated website for event capture from end users who access such designated website; receiving a selection of the event bookmarklet on the bookmark bar; displaying the event inspector panel in response to the selection of the event bookmarklet, wherein the event inspector panel is overlaid on the first page and displays any previously captured event data for any events that were previously added for such first page; receiving, via the event inspector panel, input for configuring the data contract definition including adding new events for causing event data for each new event to be captured from a plurality of end users who access the first page, wherein the data contract definition is stored as a corresponding updated data contract in a database of the universal tag configuration subsystem; a first presentation server operable to: identify the updated data contract in the database; receive the updated data contract from the database; generate runtime code instructions based on the updated data contract; and a runtime subsystem comprising: a profile server for storing the end user profiles; and a second presentation server operable to: receive the runtime code from the first presentation server to instantiate a runtime endpoint, capture, at runtime, event data from the designated website, the event data specified by the data contract definition, wherein capturing the event data includes providing a universal tag script, via the second 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; apply the transformation and taxonomy rules to the collected event data by performing an iterative loop via the runtime endpoint on the second 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; 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 the system is further configured to display, at the client machine, a data provider configuration page corresponding to the designated website, wherein the data provider configuration page is refreshed with captured event data from the plurality of end users, the event data corresponding to previously specified events.
10. The system of claim 6 , wherein the first presentation server is further operable to: responsive to adding the new events, navigate to and loading a new page of the designated website and repeating the process iteratively for the new page by starting from selecting the bookmarklet on the bookmark bar; determine no new events need to be added; responsive to determining no new events need to be added for the designated website, determine if new events for a different website need to be added and, if yes, then repeating the process iteratively by starting from entering a URL which launches a first page of the different website for event capture by end users who access such first page; determine no new events need to be added for the different website; and responsive to determining no new events need to be added for the different website, exit the graphical user interface.