Qt Essentials define the foundation of Qt on all platforms. They are available on all supported development platforms and on the tested target platforms. Except the testing modules, which will remain source compatible, these modules will remain source and binary compatible throughout Qt 6.
Essential modules are general and useful for a majority of Qt applications. A module that is used for a special purpose is considered an add-on module even if it is available on all supported platforms.
The following table lists the Qt essentials:
|Qt Core||Core non-graphical classes used by other modules.|
|Qt D-Bus||Classes for inter-process communication over the D-Bus protocol.|
|Qt GUI||Base classes for graphical user interface (GUI) components.|
|Qt Network||Classes to make network programming easier and more portable.|
|Qt Quick||A declarative framework for building highly dynamic applications with custom user interfaces.|
|Qt Quick Controls||Provides lightweight QML types for creating performant user interfaces for desktop, embedded, and mobile devices. These types employ a simple styling architecture and are very efficient.|
|Qt Quick Layouts||Layouts are items that are used to arrange Qt Quick 2 based items in the user interface.|
Note: The binary compatibility guarantee does not apply to Qt Quick Test. However, it will remain source compatible.
|Qt Test||Classes for unit testing Qt applications and libraries.|
Note: The binary compatibility guarantee does not apply to Qt Test. However, it will remain source compatible.
|Qt Widgets||Classes to extend Qt GUI with C++ widgets.|
Qt Add-On modules bring additional value for specific purposes. These modules may only be available on some development platform. Many add-on modules are either feature-complete and exist for backwards compatibility, or are only applicable to certain platforms. Each add-on module specifies its compatibility promise separately.
The Qt installers include the option of downloading the add-ons. For more information, visit the Getting Started with Qt page.
The following table lists the Qt add-ons:
|Module||Development Platforms||Target Platforms||Description|
|Qt 5 Core Compatibility APIs||Qt Core APIs that were in Qt 5 but not Qt 6.|
|Qt Concurrent||All||All||Classes for writing multi-threaded programs without using low-level threading primitives.|
|Qt Help||All||All||Classes for integrating documentation into applications.|
|Qt OpenGL||All||All||C++ classes that make it easy to use OpenGL in Qt applications. A separate library of Qt OpenGL Widgets C++ Classes provides a widget for rendering OpenGL graphics.|
|Qt for Windows, Linux, macOS||Qt for Windows, Linux, macOS, Android||Provides classes that encapsulate platform-specific information, tied to a given runtime configuration of a platform plugin.|
|Qt Print Support||All||All||Classes to make printing easier and more portable.|
|Qt Quick 3D||All||All||Provides a high-level API for creating 3D content or UIs based on Qt Quick.|
|Qt Quick Timeline||All||All||Enables keyframe-based animations and parameterization.|
|Qt Quick Widgets||All||All||Provides a C++ widget class for displaying a Qt Quick user interface.|
|Qt Shader Tools||All||All||Provides tools for the cross-platform Qt shader pipeline. These enable processing graphics and compute shaders to make them usable for Qt Quick and other components in the Qt ecosystem.|
|Qt SQL||Classes for database integration using SQL.|
|Qt SVG||All||All||Classes for displaying the contents of SVG files. Supports a subset of the SVG 1.2 Tiny standard. A separate library of Qt SVG Widgets C++ Classes provides support for rendering SVG files in a widget UI.|
|Qt UI Tools||All||All||Classes for loading QWidget based forms created in Qt Designer dynamically, at runtime.|
|Qt XML||All||All||Handling of XML in a Document Object Model (DOM) API.|
Add-ons available under Commercial Licenses, or GNU General Public License v3
|Qt Wayland Compositor||Linux||Linux and Boot to Qt targets.||Provides a framework to develop a Wayland compositor.|
Where to Go from Here
We invite you to explore the rest of Qt. We prepared overviews which help you decide which APIs to use and our examples demonstrate how to use our API.