Is Quantity Supply only for DDI users?

No, DDI is just the first ERP we integrated with — it's an example, not a requirement. Quantity Supply works without DDI, works standalone, and can connect to other ERPs, including Epicore, Spruce, Netsuite, Priority ERP, Quickbooks. The goal is to build connections to the other major ERPs distributors use, one customer at a time. If you saw it demoed with DDI, that's one setup, not the only one.