Clean core extensibility for SAP S/4HANA Cloud
Learn how the clean core strategy and the extensibility model described in this paper support this objective: Enabling customers of SAP S/4HANA Cloud to extend where needed, but still allowing for smooth system upgrades and handling of system extensions. Download the DocumentPUBLIC
Clean core extensibility
White paper
Successor to previous white paper on
extensibility: Clean core extensibility
for SAP S/4HANA Cloud
Clean core extensibility
White paper
Successor to previous white paper on
extensibility: Clean core extensibility
for SAP S/4HANA Cloud
Table of contents
Executive summary 3
1 Introduction 5
2 Why a clean core is important 7
2.1 Overcoming obstacles and
unlocking innovation 7
3 What a clean core means for 8
extensibility
3.1 Extensibility as part of the 5 guiding 8
principles of clean core
3.2 Extensibility options: On-stack 9
and side-by-side
3.2.1 On-stack: SAP Build (through ABAP 10
Cloud) or classic extensibility
3.2.2 Side-by-side with SAP Build 12
3.2.3 The best of both worlds: on-stack 15
and side-by-side extensions
3.3 SAP’s clean core extensibility model 17
and the clean core level concept
3.3.1 The clean core level concept 17
3.3.2 Evolution of 3-tier extensibility 18
to level concept
3.3.3 Overview of clean core levels 19
3.3.4 Why, what and how—Under- 20
standing the new clean core levels
3.4 Partner add-ons and clean core 24
3.4.1 SAP Solution Extensions 24
3.4.2 Clean core APIs from partners 24
4 How to achieve a clean core 25
for extensibility?
4.1 RISE with SAP Methodology 25
4.1.1 Governance and maturity— 26
An approach to assessing
clean core governance
4.1.2 Clean core measurement 27
framework
4.1.3 Measurability: Extensibility KPIs 28
4.2 Reaching clean core with
“Stay Clean” and “Get Clean” 31
4.3 Stay Clean: How to create 32
clean extensions
4.3.1 Functional requirements 32
4.3.2 Extension architecture 36
4.3.3 Extension implementation 38
4.3.4 Extension deployment 40
4.4 Get Clean: How to measure the 42
current state of clean core?
4.4.1 RISE with SAP Methodology 42
dashboard
4.4.2 Assessing clean core KPIs 43
individually
4.5 How to achieve a clean core 44
4.5.1 Key steps and recommendations 45
for your clean core journey
5 F.A.Q. 47
6 Appendix 48
2 | 50Clean core extensibility
Executive summary 3
1 Introduction 5
2 Why a clean core is important 7
2.1 Overcoming obstacles and
unlocking innovation 7
3 What a clean core means for 8
extensibility
3.1 Extensibility as part of the 5 guiding 8
principles of clean core
3.2 Extensibility options: On-stack 9
and side-by-side
3.2.1 On-stack: SAP Build (through ABAP 10
Cloud) or classic extensibility
3.2.2 Side-by-side with SAP Build 12
3.2.3 The best of both worlds: on-stack 15
and side-by-side extensions
3.3 SAP’s clean core extensibility model 17
and the clean core level concept
3.3.1 The clean core level concept 17
3.3.2 Evolution of 3-tier extensibility 18
to level concept
3.3.3 Overview of clean core levels 19
3.3.4 Why, what and how—Under- 20
standing the new clean core levels
3.4 Partner add-ons and clean core 24
3.4.1 SAP Solution Extensions 24
3.4.2 Clean core APIs from partners 24
4 How to achieve a clean core 25
for extensibility?
4.1 RISE with SAP Methodology 25
4.1.1 Governance and maturity— 26
An approach to assessing
clean core governance
4.1.2 Clean core measurement 27
framework
4.1.3 Measurability: Extensibility KPIs 28
4.2 Reaching clean core with
“Stay Clean” and “Get Clean” 31
4.3 Stay Clean: How to create 32
clean extensions
4.3.1 Functional requirements 32
4.3.2 Extension architecture 36
4.3.3 Extension implementation 38
4.3.4 Extension deployment 40
4.4 Get Clean: How to measure the 42
current state of clean core?
4.4.1 RISE with SAP Methodology 42
dashboard
4.4.2 Assessing clean core KPIs 43
individually
4.5 How to achieve a clean core 44
4.5.1 Key steps and recommendations 45
for your clean core journey
5 F.A.Q. 47
6 Appendix 48
2 | 50Clean core extensibility
Executive summary
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 chal-
lenges by promoting the use of standard, best
practiced-aligned processes and enabling strate-
gic extensions for differentiation. Process stan-
dardization supports our customers in the transi-
tion to SAP Business Suite, including the public
cloud. It enables keeping the systems current
through faster and efficient upgrades for the pri-
vate cloud, enable faster innovation cycles, and
make it easier to adopt and leverage AI. It focuses
on building resilient business processes sup-
ported by seamless integration, efficient opera-
tions, 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 readi-
ness in mind.
What is new: The evolution of the 3-tier
model—Introducing the clean core level
concept
SAP is evolving its extensibility guidelines with the
clean core level concept, a new model
designed to simplify qualification criteria and pro-
vide a more pragmatic approach to managing
custom code in SAP Cloud ERP Private1 as a part
of the journey to SAP Business Suite. By evolving
the previous 3-tier model, this 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.
This approach allows for a more granular
assessment of an extension’s quality and
upgrade stability, moving beyond a simple
binary “clean” vs. “unclean” classification.
The core recommendation remains a “SAP
BTP first” strategy, aiming for the highest
level, but the new model also acknowledges
the realities of complex system landscapes
and supports customers to tailor their clean
core journeys. The fundamental principle
remains unchanged: decouple extensions
from standard SAP code to ensure upgrade
stability.
3 | 50Clean core extensibility
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 chal-
lenges by promoting the use of standard, best
practiced-aligned processes and enabling strate-
gic extensions for differentiation. Process stan-
dardization supports our customers in the transi-
tion to SAP Business Suite, including the public
cloud. It enables keeping the systems current
through faster and efficient upgrades for the pri-
vate cloud, enable faster innovation cycles, and
make it easier to adopt and leverage AI. It focuses
on building resilient business processes sup-
ported by seamless integration, efficient opera-
tions, 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 readi-
ness in mind.
What is new: The evolution of the 3-tier
model—Introducing the clean core level
concept
SAP is evolving its extensibility guidelines with the
clean core level concept, a new model
designed to simplify qualification criteria and pro-
vide a more pragmatic approach to managing
custom code in SAP Cloud ERP Private1 as a part
of the journey to SAP Business Suite. By evolving
the previous 3-tier model, this 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.
This approach allows for a more granular
assessment of an extension’s quality and
upgrade stability, moving beyond a simple
binary “clean” vs. “unclean” classification.
The core recommendation remains a “SAP
BTP first” strategy, aiming for the highest
level, but the new model also acknowledges
the realities of complex system landscapes
and supports customers to tailor their clean
core journeys. The fundamental principle
remains unchanged: decouple extensions
from standard SAP code to ensure upgrade
stability.
3 | 50Clean core extensibility
How it works: The four clean core levels
explained
Each extension is evaluated using a standardized
methodology based on how it is built, how well it
is decoupled from the core, and how easily it can
be upgraded or maintained:
• Level A: Extend with SAP Build—Fully com-
pliant extensions using only publicly released
and stable interfaces backed by formal stability
contracts.
– Side-by-side: Built on SAP BTP using pro-
code and low-code tools for app develop-
ment and process automation.
– On-stack: Built within SAP Cloud ERP Private
using the ABAP Cloud development model
with publicly released APIs.
• Level B: Leverage classic APIs—use SAP’s
classic APIs and technologies with well-defined,
documented, and generally upgrade-stable
interfaces.
• Level C: Access internal objects—Partially
compliant extensions that rely on SAP internal
objects, offering flexibility for legacy scenarios.
To reduce upgrade risk, SAP provides the chan-
gelog for SAP objects to help identify incompat-
ible changes early and plan upgrades
proactively.
• Level D: Not recommended extensions—
Extensions not considered “clean” that use
explicitly non-recommended objects or tech-
niques (e.g., objects marked as “noAPI” in the
Cloudification Repository, modifications to SAP
objects, direct write access to SAP tables, or
implicit enhancements). These represent the
highest risk and create significant technical
debt.
Conclusion: Empowering a strategic
modernization journey
The clean core level concept delivers tangible
benefits by:
• Providing differentiated assessment: Offer-
ing a more nuanced, risk-based evaluation of
classic ABAP code.
• Increasing transparency: Clearly defining low-
risk “classic APIs” versus high-risk “not recom-
mended” objects.
• Enabling a pragmatic path forward: Helping
customers manage their existing codebases
more effectively and prioritizing remediation,
focusing first on the highest-risk extensions
(Level D).
The clean core level concept does not alter the
ultimate goal: building decoupled, upgrade-sta-
ble extensions, with Level A as the ideal. Instead,
it provides a more practical and transparent
framework to achieve it.
It empowers organizations to make informed
decisions, understand the specific risks associ-
ated with their custom code, and strategically
plan their modernization efforts. By prioritizing
the elimination of Level D extensions and leverag-
ing greater transparency around Levels B and C,
customers can reduce technical debt, simplify
future upgrades, and preserve the long-term
integrity and agility of their SAP S/4HANA core
system.
Further details of the clean core level concept
and guidance on achieving clean core for extensi-
bility are provided in the following chapters.Clean core extensibility
4 | 50
explained
Each extension is evaluated using a standardized
methodology based on how it is built, how well it
is decoupled from the core, and how easily it can
be upgraded or maintained:
• Level A: Extend with SAP Build—Fully com-
pliant extensions using only publicly released
and stable interfaces backed by formal stability
contracts.
– Side-by-side: Built on SAP BTP using pro-
code and low-code tools for app develop-
ment and process automation.
– On-stack: Built within SAP Cloud ERP Private
using the ABAP Cloud development model
with publicly released APIs.
• Level B: Leverage classic APIs—use SAP’s
classic APIs and technologies with well-defined,
documented, and generally upgrade-stable
interfaces.
• Level C: Access internal objects—Partially
compliant extensions that rely on SAP internal
objects, offering flexibility for legacy scenarios.
To reduce upgrade risk, SAP provides the chan-
gelog for SAP objects to help identify incompat-
ible changes early and plan upgrades
proactively.
• Level D: Not recommended extensions—
Extensions not considered “clean” that use
explicitly non-recommended objects or tech-
niques (e.g., objects marked as “noAPI” in the
Cloudification Repository, modifications to SAP
objects, direct write access to SAP tables, or
implicit enhancements). These represent the
highest risk and create significant technical
debt.
Conclusion: Empowering a strategic
modernization journey
The clean core level concept delivers tangible
benefits by:
• Providing differentiated assessment: Offer-
ing a more nuanced, risk-based evaluation of
classic ABAP code.
• Increasing transparency: Clearly defining low-
risk “classic APIs” versus high-risk “not recom-
mended” objects.
• Enabling a pragmatic path forward: Helping
customers manage their existing codebases
more effectively and prioritizing remediation,
focusing first on the highest-risk extensions
(Level D).
The clean core level concept does not alter the
ultimate goal: building decoupled, upgrade-sta-
ble extensions, with Level A as the ideal. Instead,
it provides a more practical and transparent
framework to achieve it.
It empowers organizations to make informed
decisions, understand the specific risks associ-
ated with their custom code, and strategically
plan their modernization efforts. By prioritizing
the elimination of Level D extensions and leverag-
ing greater transparency around Levels B and C,
customers can reduce technical debt, simplify
future upgrades, and preserve the long-term
integrity and agility of their SAP S/4HANA core
system.
Further details of the clean core level concept
and guidance on achieving clean core for extensi-
bility are provided in the following chapters.Clean core extensibility
4 | 50
1 Introduction
SAP software is designed to deliver broad and
deep functionality across lines of business and
industries.
At the core of this breadth is the synergy of appli-
cations, data, and AI. Think of a flywheel that
builds continuous momentum: applications gen-
erate the data, data provides trusted context, and
AI turns that context into action. Each action
feeds the next, driving resilience, efficiency, and
growth.
The clean core approach
However, no two businesses are exactly alike, and
true differentiation often requires more than just
standard processes. SAP recognizes this and
enables customers to extend its solutions in ways
that foster innovation while preserving the stabil-
ity of the core system.
The SAP Business Suite brings this synergy to life. It
provides an integrated cloud portfolio that spans
ERP and line-of-business applications, unified by a
common data foundation and embedded, indus-
try-specific AI, all underpinned by a business tech-
nology platform for integration, automation, and
extensibility. Together, these capabilities connect
and optimize every function across the enterprise,
ensuring AI is grounded in reliable data and exe-
cuted through proven processes, rather than
applied as an isolated wrapper.
This balance between standardization and differ-
entiation lies at the heart of SAP’s clean core
strategy. Clean core encourages organizations to
adopt standardized, upgrade-stable functionality
for non-differentiating processes, while providing
flexible extensibility options for capabilities that
deliver unique business value. It is about
Figure 1: SAP Business Suite
5 | 50Clean core extensibility
SAP software is designed to deliver broad and
deep functionality across lines of business and
industries.
At the core of this breadth is the synergy of appli-
cations, data, and AI. Think of a flywheel that
builds continuous momentum: applications gen-
erate the data, data provides trusted context, and
AI turns that context into action. Each action
feeds the next, driving resilience, efficiency, and
growth.
The clean core approach
However, no two businesses are exactly alike, and
true differentiation often requires more than just
standard processes. SAP recognizes this and
enables customers to extend its solutions in ways
that foster innovation while preserving the stabil-
ity of the core system.
The SAP Business Suite brings this synergy to life. It
provides an integrated cloud portfolio that spans
ERP and line-of-business applications, unified by a
common data foundation and embedded, indus-
try-specific AI, all underpinned by a business tech-
nology platform for integration, automation, and
extensibility. Together, these capabilities connect
and optimize every function across the enterprise,
ensuring AI is grounded in reliable data and exe-
cuted through proven processes, rather than
applied as an isolated wrapper.
This balance between standardization and differ-
entiation lies at the heart of SAP’s clean core
strategy. Clean core encourages organizations to
adopt standardized, upgrade-stable functionality
for non-differentiating processes, while providing
flexible extensibility options for capabilities that
deliver unique business value. It is about
Figure 1: SAP Business Suite
5 | 50Clean core extensibility