xtd (pronounced "extend") is a modern C++17/20 framework to create console, GUI (forms like WinForms) and unit test applications on Microsoft Windows, Apple macOS, Linux, iOS and android.
tunit
Modern c++17 unit testing framework on Windows macOS, Linux, iOS and android.
delegates
Modern c++17 library containing multicast delegate and event classes on Windows, macOS, Linux, iOS and android.
properties
another c#-like property accessor for C++11 and above.