# SAP Custom API Integration — BAPI, RFC, OData, and IDoc Without SAP PI/PO Overhead Custom SAP API integration means connecting non-SAP applications (your CRM, your e-commerce platform, your warehouse system, your data warehouse) to your SAP ECC or S/4HANA system using SAP's native integration interfaces — BAPIs for synchronous business transactions, RFCs for low-level function calls, OData services for REST-style access, and IDocs for asynchronous document exchange. FreedomDev has been building these integrations for mid-market companies since SAP NetWeaver was new. We do this without forcing you to deploy SAP Process Integration (PI/PO) or SAP Integration Suite — middleware layers that cost more than the rest of your integration project and require dedicated SAP basis expertise to maintain. Lightweight, direct, and your engineers can read the code. ## SAP Custom API Integration — BAPI, RFC, OData, and IDoc Without SAP PI/PO Overhead Custom SAP API integration means connecting non-SAP applications (your CRM, your e-commerce platform, your warehouse system, your data warehouse) to your SAP ECC or S/4HANA system using SAP's native integration interfaces — BAPIs for synchronous business transactions, RFCs for low-level function calls, OData services for REST-style access, and IDocs for asynchronous document exchange. FreedomDev has been building these integrations for mid-market companies since SAP NetWeaver was new. We do this without forcing you to deploy SAP Process Integration (PI/PO) or SAP Integration Suite — middleware layers that cost more than the rest of your integration project and require dedicated SAP basis expertise to maintain. Lightweight, direct, and your engineers can read the code. --- ## Our Process --- ## Frequently Asked Questions ### How do I create a custom API in SAP? (PAA capture) Depends on your SAP deployment. On S/4HANA Cloud Public Edition: create a CDS projection view, then a service definition, then bind it to expose as an OData API. On S/4HANA on-prem or Cloud Private: same path, or use the older SAP Gateway approach with custom OData services, or expose RFC-enabled function modules. On classic ECC: create RFC-enabled function modules or use existing BAPIs. The full process, including authentication and Communication Arrangement setup, runs about 4-6 weeks for a non-trivial API. ### Does SAP have API integration? (PAA capture) Yes, multiple integration interfaces depending on the use case. BAPIs for business-level synchronous APIs. RFC for lower-level function calls. OData for REST/JSON access. IDoc for asynchronous bulk document exchange. SAP also provides middleware platforms (Process Integration/Orchestration, Integration Suite on BTP) but those are optional — direct integration using the protocols above is fully supported and often the better choice for mid-market deployments. ### What is custom API integration? (PAA capture) Custom API integration is the bespoke work of connecting your non-SAP applications to SAP using SAP's native interfaces, tailored to your specific data flows and business processes rather than using a generic connector. The custom layer is needed because most real integration scenarios involve mappings between your external system's data model and SAP's data model — transformations, business rules, error handling — that off-the-shelf connectors cannot anticipate. ### What are the four types of REST APIs? (PAA capture) The four most common API styles encountered in enterprise integration are REST, SOAP, GraphQL, and gRPC. REST itself does not have "four types" in any formal sense; the question is sometimes confused with the four HTTP verbs (GET, POST, PUT/PATCH, DELETE) or with four API patterns (open/public, partner, internal, composite). For SAP integration specifically, the protocols are BAPI/RFC (SOAP-derived), OData (REST), and IDoc (asynchronous document) — not REST sub-types. ### How long does an SAP custom API integration project take? Single-integration scope: 6-10 weeks discovery to production. Multi-integration project (3-5 systems): 12-20 weeks. The variability is driven by SAP-side discovery (figuring out which BAPI/RFC/OData service exists for your needed flow) and authentication setup (Communication Users and Arrangements on S/4HANA Cloud) more than by the integration service development itself. ### Why do you recommend against SAP PI/PO for mid-market companies? Cost and overhead. SAP PI/PO licensing runs $80k-$300k+ and requires dedicated SAP basis expertise to maintain. For a mid-market company integrating 3-5 external systems with SAP, the PI/PO platform costs more than the integration work it is supposed to enable. Direct integration using BAPI/RFC/OData/IDoc, deployed as a lightweight service in your existing stack, gets the same business outcome at a fraction of the cost and is maintainable by your existing engineering team. PI/PO is the right choice for large enterprises with 20+ integrated systems; for everyone else it is overhead. ### Can FreedomDev work with SAP Integration Suite (BTP)? Yes. If you have SAP BTP and have committed to Integration Suite as your platform, we can build integration flows there using Cloud Integration (iFlows) and API Management. The work is similar but the deliverable is iFlow content packages instead of standalone services. Our usual recommendation: skip Integration Suite for mid-market unless you have a specific reason (large enterprise scale, dedicated SAP basis team, regulatory requirements for centralized message logging). --- **Canonical URL**: https://freedomdev.com/solutions/sap-custom-api-integration _Last updated: 2026-05-12_