| Baloo | Baloo is a file indexing and searching framework | Development | LGPLv2.1+ | |
| CuteTest | Unit testing for Qt | Development | LGPLv3+, BSD-3-clause, Apache-2.0 | |
| Extra CMake Modules | Extra CMake modules | Development | LGPLv2.1+ | |
| GCF | Generic component framework | Development | GPLv2, GPLv3, Commercial | |
| injeqt | Dependency injection | Development | LGPLv2.1 | |
| KConfig | Configuration system | Development | LGPLv2.1+ | |
| KConfigWidgets | Widgets for configuration dialogs | Development, Widgets | LGPLv2.1+ | |
| KCrash | Support for application crash analysis and bug report from apps | Development | LGPLv2.1+ | |
| KDDockWidgets | Qt dock widget library | API, Development | GPLv2.0+, Commercial | |
| KDELibs 4 Support | Porting aid from KDELibs4 | Development | LGPLv2.1+ | |
| KDesignerPlugin | Tool to generate custom widget plugins for Qt Designer/Creator | Development | LGPLv2.1+ | |
| KDocTools | Documentation generation from docbook | Development, Text | LGPLv2.1+ | |
| KD SOAP | Client-side and server-side SOAP component | API, Development | LGPLv2.1+, Commercial | |
| KF5Umbrella | CMake convenience functions for KDE Frameworks | Development | LGPLv2.1+ | |
| KI18n | Advanced internationalization framework | Development, Text | LGPLv2.1+ | |
| KItemModels | Models for Qt Model/View system | Development | LGPLv2.1+ | |
| KItemViews | Widget addons for Qt Model/View | Widgets, Development | LGPLv2.1+ | |
| Kode | Code generation library | Development, Data | LGPLv2.1+ | |
| KPackage Framework | Library to load and install packages of non binary files as they were a plugin | Development | LGPLv2.1+ | |
| KService | Advanced plugin and service introspection | Development | LGPLv2.1+ | |
| Qxt | Utility classes for Qt | Development, Widgets | BSD-3-Clause | |
| Log4Qt | C++ port of the Log4j logging framework | Development, Logging | Apache-v2.0 | |
| Log4Qt | C++ port of the Log4j logging framework | Development, Logging | Apache-2.0 | |
| Mime Type | Backport of the Qt 5 mimetypes api to Qt 4 | Development | LGPLv2.1, GPLv3 | |
| Noron | Remote object sharing | Development | GPLv3, LGPLv3 | |
| Novile | Source code editor component for Qt | Development, Text | GPL | |
| qlogsystem | qlogsystem is a very efficient and easy to use logger library | Development, Logging | LGPLv2.1 | |
| QSkinny | lightweight Qt UI library | Development | LGPLv2 | |
| QsLog | Simple Qt logger | Logging, Development | BSD-3-Clause | |
| QtAccountsService | Qt-style API for freedesktop.org's AccountsService DBus service | Development | LGPLv3+ | |
| QtArg | Command line parsing | Development | MIT | |
| Qt Installer Framework | Tools and utilities to create installers for the supported desktop Qt platforms. | Development | LGPLv2.1+ | |
| QtIOCContainer | Application framework inspired by Inversion Of Control concept | Development | LGPLv2 | |
| QtModeling | Framework for supporting model-driven engineering | Development | LGPLv2.1, GPLv3 | |
| qtoptimization | Module for optimization algorithms | Development | LGPLv2.1, GPLv3 | |
| QtPromise | Promises/A+ implementation for Qt/C++ | Data, Development | MIT | |
| QtSharp | Mono/.NET bindings for Qt | Development | Apache-v2.0 | |
| Solid | Hardware integration and detection | Development | LGPLv2.1+ | |
| Tasks | a simple single header library that allows async programming in Qt/C++ using tasks and continuations | Development | BSD | |
| ThreadWeaver | High-level multithreading framework | Development | LGPLv2.1+ |