ERP depends on integrations. Without connections to finance, e-commerce, machines, or document management systems, gaps and duplicate data entry appear. An integration concept belongs in the planning phase, not on the backlog after go-live.

Typical connections in mid-market companies:

• DATEV (the standard interface used by German accounting firms) and financial data export for accounting and tax advisors
• XRechnung and ZUGFeRD for e-invoicing (details)
• REST APIs for webshops, CRM, or BI
• Machines and MES in manufacturing companies
• Document management systems for audit-proof archiving

Clarify before selection: which systems stay, and which does ERP replace? Which data flows in which direction? Who maintains the interface through updates?

Proprietary ERP systems often ship only a limited set of connectors. Open platforms allow custom integrations without vendor approval. Documentation and testing keep integrations running for years.

Missing interfaces are a common mistake in ERP implementations. For sovereignty, what counts is: integrations documented, maintainable, and independent of any single provider.