Agar Alternatives

Powerful, flexible and easy to use, Qt will help you not only meet your tight deadline, but also reduce the maintainable code by an astonishing percentage.

wxWidgets: Cross-Platform GUI Library

GTK+ is a multi-platform toolkit for creating graphical user interfaces.

fox-toolkit.org

Fast Light Toolkit - Fast Light Toolkit (FLTK)

Build Mobile, Desktop and WebAssembly apps with C# and XAML.

gtkmm is the official C++ interface for the popular GUI library GTK+.

Open source Python framework for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps. Installation on WindowsInstallation on Windows. Installation; What are wheels .

Qt for Python - Qt Wiki

A multi-platform .NET UI framework

Riverbank | Software | PyQt | What is PyQt?

Qt Creator is a cross-platform C++, JavaScript and QML integrated development environment. It is the fastest, easiest and most fun experience a C++ developer could wish for.

JavaFX is the next step in the evolution of Java as a rich client platform.