If you have ever worked with C++ for GUI development, chance are that you have heard of Qt. Qt is a free and open source widget toolkit for creating GUI and cross platform applications that run on many platforms such as Linux, Windows, MacOs, Android, etc… with native capabilities and performances. Qt does not provide only GUI API but has also support for networking, audio, serial port, thread, database, etc… It’s one of the biggest framework ever written for C++.