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 Dialogs||Types for creating and interacting with system dialogs from a Qt Quick application.|
|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|
|Active Qt||Windows||Windows||Classes for applications which use ActiveX and COM|
|Qt 3D||All||All||Functionality for near-realtime simulation systems with support for 2D and 3D rendering.|
|Qt 5 Core Compatibility APIs||All||All||Qt Core APIs that were in Qt 5 but not Qt 6.|
|Qt Bluetooth||All||Android, iOS, Linux, Boot to Qt, macOS and Windows||Provides access to Bluetooth hardware.|
|Qt CoAP||All||All||Implements the client side of CoAP defined by RFC 7252.|
|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 Image Formats||All||All||Plugins for additional image formats: TIFF, MNG, TGA, WBMP.|
|Qt Multimedia||All||All*||A rich set of QML types and C++ classes to handle multimedia content. Also includes APIs to handle camera access.|
|Qt NFC||All||Android and iOS||Provides access to Near-Field communication (NFC) hardware.|
|Qt OPC UA||All||All (except QNX, WebAssembly)||Protocol for data modeling and exchange of data in industrial 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 Positioning||All||Android, iOS, macOS, Linux and Windows||Provides access to position, satellite info and area monitoring classes.|
|Qt Print Support||All||All||Classes to make printing easier and more portable.|
|Qt Quick Widgets||All||All||Provides a C++ widget class for displaying a Qt Quick user interface.|
|Qt Remote Objects||All||All||Provides an easy to use mechanism for sharing a QObject's API (Properties/Signals/Slots) between processes or devices.|
|Qt SCXML||All||All||Provides classes and tools for creating state machines from SCXML files and embedding them in applications.|
|Qt Sensors||All||Android, iOS, and Windows||Provides access to sensor hardware.|
|Qt Serial Bus||All||Linux, Boot to Qt, macOS and Windows||Provides access to serial industrial bus interfaces. Currently, the module supports the CAN bus and Modbus protocols.|
|Qt Serial Port||All||Linux, Boot to Qt, macOS and Windows||Provides classes to interact with hardware and virtual serial ports.|
|Qt SQL||All||All||Classes for database integration using SQL.|
|Qt State Machine||All||All||Provides classes for creating and executing state graphs.|
|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 WebEngine||All||Windows, Linux, and macOS.||Classes and functions for embedding web content in applications using the Chromium browser project.|
|Qt WebSockets||All||All||Provides WebSocket communication compliant with RFC 6455.|
|Qt WebView||All||Platforms with a native web engine.||Displays web content in a QML application by using APIs native to the platform, without the need to include a full web browser stack.|
|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 Charts||All||All||UI Components for displaying visually pleasing charts, driven by static or dynamic data models.|
|Qt Data Visualization||All||All||UI Components for creating stunning 3D data visualizations.|
|Qt Lottie Animation||All||All||A QML API for rendering graphics and animations in JSON format, exported by the Bodymovin plugin for Adobe® After Effects.|
|Qt MQTT||All||All||Provides an implementation of the MQTT protocol specification.|
|Qt Network Authorization||All||All||Provides support for OAuth-based authorization to online services.|
|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 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 Virtual Keyboard||All||Linux and Windows desktop, and Boot to Qt targets.||A framework for implementing different input methods as well as a QML virtual keyboard. Supports localized keyboard layouts and custom visual themes.|
|Qt Wayland Compositor||Linux||Linux and Boot to Qt targets.||Provides a framework to develop a Wayland compositor.|
Note: All* refers to all supported platforms except QNX and INTEGRITY.
The following add-ons are still in development, but are available as technology previews:
|Module||Development Platforms||Target Platforms||Description|
|Qt PDF||All||Windows, Linux, and macOS.||Classes and functions for rendering PDF documents.|
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.
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