SAP Master Data Governance (MDG) is a product portfolio from SAP for governing master data across an SAP landscape. It supports data quality management, consolidation and central governance for domains such as business partner, product and financial data, and allows custom domains. MDG is aligned with the SAP S/4HANA roadmap. It can be deployed as a central hub, to which master data from one or more systems is fed for verification before being replicated back, or co-deployed on one or more S/4HANA systems. A classic mode and a cloud-ready mode with Fiori interfaces are available.
SAP is a German software company. Where the data resides depends on the chosen variant: MDG can run on an organisation's own S/4HANA systems, as part of S/4HANA Cloud Private or Public Edition, or as a complementary SaaS option (MDG cloud edition). In your own landscape the organisation decides the location itself; with SAP cloud variants it follows from the contractual arrangements with SAP. The software is proprietary and not open source.