Access to the Global Index requires a paid subscription to a Diffbot Plus, Professional or Enterprise plan. Each plan provides a monthly allotment of Global Index search queries in addition to regular extraction API calls.
The Global Index is built atop the Diffbot Search API and is populated by Diffbot’s Article and Discussion APIs; as such, API syntax and data output are consistent with the rest of the Diffbot platform.
Our updated Developer Dashboard — scheduled for a mid-2017 release — also offers a UI for performing Global Index searches. Contact us if you are interested in acquiring beta access to the new Dashboard.