Multi-system accounts payable integration architecture unifying SAP S/4HANA, Ariba, Maximo, and OpenText through SAP Business Technology Platform. Data flows from Vendor Portal Users, Procurement Users, and Maintenance Users through BTP Integration Suite, API Management, and Event Mesh to orchestrate invoice capture, validation, PO matching, and GL posting across FI-AP, Purchasing, and Asset Management modules. This hub-and-spoke pattern eliminates point-to-point integrations, enforces audit compliance, and centralizes identity and credential management via BTP Identity Provider and Credential Store. Fork this diagram to customize integration flows, add additional SAP modules, or adapt for your vendor ecosystem and payment workflows. The architecture demonstrates enterprise-grade separation of concerns with dedicated layers for presentation, integration, application logic, and data persistence.