
Previously, in Unit 2 Lesson 2, Evaluating SAP Build, we discussed that the emergence of the citizen developer has transformed application development. Key user extensibility is oriented towards those whose personas fall within the scope of citizen development, that is, the use of low-code/no-code tools to accomplish their tasks. These personas would therefore also include business experts, key users, and potentially other types of roles.
Key user (formerly known as in-app) extensibility options cover a wide range of use cases. The tools used to create key user extensions are not dependent on the citizen developer understanding any of the underlying technical details of the SAP application being extended. The focus is on quick implementation and deployment of simple extensions using low-code/no-code tools. All of the tools are Web-based SAP Fiori apps, available in all SAP S/4HANA deployment options, and when used, are consistent with the clean core approach.

Briefly summarized, the tools and capabilities are as follows:
- User Interface (UI) Adaption at Runtime: A key user can adapt a UI at runtime. For example, a field label can be changed to a country-specific value, or a new field can be added to the display.
- Custom Fields: Using this tool, a key user can create and edit custom fields for SAP tables, Core Data Service (CDS) views or OData services.
- Custom Business Logic: This tool enables a key user to enhance SAP S/4HANA Cloud functionality by adding additional business logic. The logic goes in an underlying enhancement point (the specifics of which are hidden from the key user) and the tool includes a Web-based ABAP editor with code completion, syntax checking, and testing capabilities.
- Custom Business Object (BO): With this tool, key users can go one step further than custom business logic. Entirely new BOs can be created along with their associated database tables. In addition, an API for create, read, update, and deletion of data can be created.
- Custom CDS View: A key user can use this tool to model access to data in a way that existing CDS views may not to support reporting or custom business logic efforts.
- Custom Analytical Queries: Queries are one of the foundations of reporting. The Custom Analytical Query tool allows them to be created easily by key users based off of SAP or customer-created data sources.
- KPIs: Similar to queries, KPIs are an important part of reporting. With the KPI set of tools, key users can design new KPIs visualized as tiles in the SAP Fiori launchpad with drill-down capabilities.
- Forms: Finally, to support form and email-based process implementations, the Custom Forms tool allows key users to create form and email templates based off of SAP data sources such as CDS views and OData services.