Many SAP systems became hard to upgrade because of deep modifications to the standard code. Clean core is SAP's principle to avoid that in S/4HANA: keep the core as close to the standard as possible and build extensions in an upgrade-safe way.
Why it matters
- Faster, cheaper upgrades
- Easier adoption of new SAP innovations
- Lower risk of errors after updates
- A prerequisite for cloud editions
Extension options
Key-user extensibility
Business experts add custom fields, logic and forms with in-app tools – no coding required. Ideal for small adjustments.
Developer extensibility (on-stack)
Developers build extensions inside S/4HANA using ABAP Cloud: released APIs, the RESTful ABAP Programming Model (RAP) and CDS views. These extensions stay stable across upgrades.
Side-by-side extensibility on SAP BTP
Separate applications run on SAP Business Technology Platform and communicate with S/4HANA via APIs and events. Good for new apps, portals, mobile apps and integrations with non-SAP systems.
Choosing the right option
| Need | Recommended |
|---|---|
| Extra field or simple rule | Key-user extensibility |
| Logic tightly connected to SAP data | ABAP Cloud (on-stack) |
| New application or external users | BTP side-by-side |
| Integration with other systems | Integration Suite / APIs |
Dealing with existing custom code
In conversions, analyse custom code, remove unused developments, adapt what's needed and, over time, move modifications to clean extension models.
Governance
Define rules for when and how extensions are built, document them and review regularly. Clean core is a continuous practice, not a one-time cleanup.
We build ABAP Cloud, Fiori and BTP extensions that respect clean core – so your system stays upgradeable.