If you know the name of the class you want, find it here.
A list of all C++ API components in Qt 5
A list of all modules in Qt 5.
A Qt namespace contains enum types, functions, and sometimes classes.
A list of QML basic types in this Qt release.
A list of all QML modules in Qt 5.
A list of QML types in this Qt release.
If you don't know the name of the class you want, but you know what the class should do, you might try looking here.
The C++ class inheritance hierarchy for all classes in the Qt API.
Classes and members marked obsolete that should not be used in new code.
A list of obsolete QML types that should not be used in new code.
If you know what kind of class you want (GUI, painting, I.O, etc), look here
The <QtAlgorithms> header includes the generic, template-based algorithms.
The <QtEndian> header provides functions to convert between little and big endian representations of numbers.
The <QtGlobal> header file includes the fundamental global declarations. It is included by most other Qt header files.
The <QtMath> header file provides various math functions.
All documented Qt functions listed alphabetically with a link to where each one is declared.
Provides information about Android support in Qt.
Provides information about Embedded Linux support in Qt.
Platform support for INTEGRITY.
Platform support for Linux/X11.
Platform support for VxWorks (under a commercial license).
Provides insight into Qt's WinRT port and how to use it.
Platform support for Windows.
Provides insight into Qt's iOS port and how to use it.
Platform support for macOS. macOS (previously known as OS X or Mac OS X) is a UNIX platform and behaves similarly to other Unix-like platforms. The main difference is that X11 is not used as the windowing system. Instead, macOS uses its own native windowing system that is accessible through the Cocoa API. Application development on macOS is done using Xcode, which is available from https://developer.apple.com/xcode/.