Innovation is critical — but without the right foundation, it can quickly lead to complexity and cost. SAP’s clean core strategy helps customers build and extend their SAP S/4HANA Cloud systems in a way that is stable, agile, and innovation-ready.
The goal is simple: keep the core clean, standard, and upgrade-stable while still enabling business-specific differentiation where it counts.
Why clean core matters
Over time, many ERP landscapes become weighed down by custom code, undocumented changes, and hard-to-maintain integrations. This limits flexibility, slows down upgrades, and increases the total cost of ownership.
The clean core approach addresses these challenges by promoting the use of standard processes and enabling strategic extensions for differentiation. It focuses on building resilient business processes supported by seamless integration, efficient operations, and strong data quality.
By embracing a clean core approach, customers can:
- Accelerate innovation cycles
- Minimize technical debt
- Simplify system maintenance and upgrades
Rather than limiting agility, clean core ensures that extensions are done the right way — with long-term stability, scalability, and innovation-readiness in mind.
Clean extensions: build what you need, without risk
Business differentiation often depends on tailored processes, custom applications, or personalized user experiences. SAP supports this through clean extensibility, a framework that enables innovation without compromising system integrity.
Extend SAP S/4HANA Cloud using:
- Side-by-side extensibility on SAP Business Technology Platform (SAP BTP): creating scalable, decoupled applications that run independently from the core.
- On-stack extensibility with ABAP Cloud: tightly integrated, upgrade-stable extensions within the ERP system
Both models ensure flexibility while keeping systems clean, secure, and easier to maintain. Choose between side-by-side and on-stack extensibility based on your use case, applying an SAP BTP-first strategy.
Clean core level concept: clarity and control
To clarify extensibility decisions and simplify qualification criteria, SAP has evolved its original three-tier model into the clean core level concept, an enhanced maturity model that brings greater structure, flexibility, and transparency. It also provides a more pragmatic approach to managing custom code in SAP S/4HANA Cloud.
The new maturity model categorizes extensions into four distinct levels (A, B, C, and D) based on their architectural integrity, upgrade safety, and alignment with clean core principles. The evolved framework empowers organizations to make smarter decisions, streamline development, and continuously optimize their extensions — with more clarity, confidence, and long-term control.
Each extension is evaluated using a standardized methodology that looks at how the extension is built, how well it is decoupled from the core, and how easily it can be upgraded or maintained.
The model defines four levels of compliance:
- Level A – Extend with SAP Build: Fully compliant extensions using only publicly released and stable SAP interfaces, backed by formal stability contracts.
- Side-by-side: Built on SAP BTP, using pro-code and low-code tools for app development and process automation.
- On-stack: Built within SAP S/4HANA Cloud using the ABAP Cloud development model with publicly released APIs.
- Level B – Leverage classic APIs: Compliant extensions, in addition to meeting level A criteria, using also SAP’s classic APIs and technologies. These APIs offer well-defined, documented, and generally upgrade-stable interfaces for extension use.
- Level C – Accesses internal objects: Partially compliant extensions allowing access to SAP internal objects, offering flexibility for legacy scenarios. To minimize upgrade risks, SAP plans to provide a changelog for SAP objects to help identify changes early and plan upgrades proactively.
- Level D – Not recommended extensions: Extensions not considered “clean” that use explicitly non-recommended objects or techniques; for example, explicitly non-recommended objects, modifications, write access to SAP tables, or implicit enhancements. These represent the highest risk and create significant technical debt.
By assigning each extension to a compliance level, the clean core level concept gives IT leaders, enterprise architects, and business stakeholders a shared vocabulary and visual road map for assessing their current ERP landscape. It supports transparent decision-making regarding where to invest in cleanup, modernization, or new development.
How SAP supports your journey to clean extensions
SAP offers a full set of technologies to support clean, upgrade-safe extensions and provide clean core insights:
- SAP BTP serves as the foundation for side-by-side extensions, enabling development, automation, and integration.
- SAP Build is a unified application development and process automation solution for developing apps, AI agents, and automations using pro-code, low-code, and generative AI — enabling personalization and efficiency at scale.
- ABAP Cloud, part of SAP Build, supports both on-stack and side-by-side development, enabling the enforcement of clean principles through syntax checks and lifecycle support.
- Joule, SAP’s AI copilot, boosts developer productivity by generating clean, context-aware code and streamlining workflow automation across ABAP, Java, JavaScript, and low-code tools.
- The RISE with SAP Methodology dashboard provides real-time insights into clean core adoption.
- For detailed code-level governance, the ABAP test cockpit is the key tool.
Smarter way to extend
Supported by the level concept and a powerful set of extensibility tools, SAP’s clean core strategy empowers organizations to innovate faster, increase agility, and lower total cost of ownership.
Extend what sets you apart: Decoupled extensions simplify upgrades and accelerate innovation. That’s one advantage of clean core.
Learn more at sap.com/clean-core.
Priyadarsana Panda is senior vice president and general manager of Cloud ERP Solution Area at SAP.
Steffen Pietsch is vice president and head of SAP BTP Product Management at SAP.
Rudolf Hois is senior vice president and chief product owner of Cloud ERP Private at SAP.
