KNotifyConfig provides a configuration dialog for desktop notifications which
can be embedded in your application.

A library that provides access to all contacts and the people who hold them.

KPlotting

Kross

KtoBLZCheck is a library to check account numbers and bank codes of German banks. Both a library for other programs as well as a short command-line tool is available. It is possible to check pairs of account numbers and bank codes (BLZ) of German banks, and to map bank codes (BLZ) to the clear-text name and location of the bank.

libalkimia is a library with common classes and functionality used by finance
applications for the KDE SC.

This library provides a Qt implementation of the DBusMenu protocol.

The DBusMenu protocol makes it possible for applications to export and import
their menus over DBus. Qt5 library

VulkanSceneGraph (VSG), is a modern, cross platform, high performance scene graph library built upon Vulkan graphics/compute API. The software is written in C++17, and follows the CppCoreGuidlines and FOSS Best Practices. The source code is published under the MIT License.

Ngspice is a mixed-level/mixed-signal circuit simulator. Its code is based on three open source software packages: Spice3f5, Cider1b1 and Xspice.