  Low-code development platforms provide an accessible infrastructure for the
creation of software by domain experts, also called "citizen developers",
without the need for formal programming education. Development is facilitated
through graphical user interfaces, although traditional programming can still
be used to extend low-code applications, for example when external services or
complex business logic needs to be implemented that cannot be realized with the
features available on a platform. Since citizen developers are usually not
specifically trained in software development, they require additional support
when writing code, particularly with regard to security and advanced techniques
like debugging or versioning. In this thesis, several options to assist
developers of low-code applications are investigated and implemented. A
framework to quickly build code editor extensions is developed, and an approach
to leverage the Roslyn compiler platform to implement custom static code
analysis rules for low-code development platforms using the .NET platform is
demonstrated. Furthermore, a sample application showing how Roslyn can be used
to build a simple, integrated debugging tool, as well as an abstraction of the
version control system Git for easier usage by citizen developers, is
implemented. Security is a critical aspect when low-code applications are
deployed. To provide an overview over possible options to ensure the secure and
isolated execution of low-code applications, a threat model is developed and
used as the basis for a comparison between OS-level virtualization, sandboxing,
and runtime code security implementations.
