SAP S/4HANA
What is Clean Core?
SAP's principle of keeping ERP code and configuration close to standard, with extensions built only through stable, released interfaces.
A clean core reduces upgrade effort because custom code does not depend on SAP internals that can change. It is achieved through key-user and on-stack ABAP Cloud extensibility, side-by-side extensions on BTP, and released APIs. For testers, a cleaner core means smaller regression scope per upgrade, while legacy modifications remain high-risk test areas.
Related terms
Clean Core Level A
Extensions using only released, upgrade-stable APIs and extension points under ABAP Cloud or key-user tools; the target state.
Clean Core Level B
Extensions using classic APIs and techniques that SAP lists as stable but not formally released for ABAP Cloud.
Clean Core Level C
Extensions that use internal, unreleased SAP objects; possible but at risk of breaking during upgrades.
Clean Core Level D
Not-recommended extension techniques such as modifications, implicit enhancements, or direct writes to SAP tables.
ABAP Cloud
SAP's development model using a restricted ABAP language version, released APIs only, ADT, and RAP for upgrade-stable code.
Side-by-Side Extensibility
Building extensions on SAP BTP that interact with S/4HANA through released APIs and events rather than inside the ERP.
Released API
An SAP object such as an API, CDS view, or BAdI that SAP marks as stable for customer use with a release contract.
More in SAP S/4HANA
Planning an S/4HANA move?
Read the field guides on testing an ECC to S/4HANA migration and grab the free template library.