wxWidgets is described as 'C++ library that lets developers create applications for Windows, OS X, Linux and UNIX on 32-bit and 64-bit architectures as well as several mobile platforms including Windows Mobile, iPhone SDK and embedded GTK+' and is an app in the development category. There are more than 25 alternatives to wxWidgets for a variety of platforms, including Windows, Linux, Mac, BSD and Android apps. The best wxWidgets alternative is Qt, which is both free and Open Source. Other great apps like wxWidgets are Electron, GTK, Photino and Avalonia UI.
IUP is a multi-platform toolkit for building graphical user interfaces. It offers a simple API in three basic languages: C, Lua and LED. IUP's purpose is to allow a program source code to be compiled in different systems without any modification.
PyGTK lets you to easily create programs with a graphical user interface using the Python programming language. The underlying GTK+ library provides all kind of visual elements and utilities for it and, if needed, you can develop full featured applications for the GNOME Desktop.
azula is a lightweight alternative to Electron. It is based on Ultralight, which is an embedding friendly Fork of WebKit, with less memory usage and low disk space requirements.
The FOX toolkit is an open source, cross-platform widget toolkit, that is, a library of basic elements for building a graphical user interface (GUI).
Gio is a library for writing cross-platform immediate mode GUI-s in Go. Gio supports all the major platforms: Linux, macOS, Windows, Android, iOS, FreeBSD, OpenBSD and WebAssembly.
Elements C++ GUI is a modern C++ (esp. C++14 and C++17) UI library. Featuring resolution independence and HDPI support, with modularity as another focal point, the library is made for general purpose use while also covering everything needed for audio plugin development.
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