Qt Reference Pages
If you know the name of the class you want, find it here.
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.
If you know what kind of class you want (GUI, painting, I.O, etc), look 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.
A Qt namespace contains enum types, functions, and sometimes classes.
A list of all C++ API components in Qt 5
A list of all QML API in Qt 5
A list of all modules in Qt 5.
All documented Qt functions listed alphabetically with a link to where each one is declared.
Exported functions for fine tuning Qt applications.
Qt Tool Manuals
Platform support for Linux/X11.
Platform support for Mac OS X.
Platform support for Windows.