Apps similar to Qt include Electron, which is free and open source. Other options are Flutter, React, React Native and Tauri. There's no shortage of Software Frameworks like Qt, with more than 50 alternatives for Windows, Linux, Mac, Android and self-hosting.
The Standard Widget Toolkit (SWT) is an open source widget toolkit for Java designed to provide efficient, portable access to the user-interface facilities of the operating systems on which it is implemented.
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gtkmm is the official C++ interface for the popular GUI library GTK+. Highlights include typesafe callbacks, and a comprehensive set of widgets that are easily extensible via inheritance. You can create user interfaces either in code or with the Glade User Interface designer...
pywebview is a lightweight cross-platform wrapper around a webview component that allows to display HTML content in its own native GUI window. You may think of as Electron for Python (minus huge executable sizes).
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The Fast, Light Toolkit (FLTK, pronounced fulltick) is a cross-platform graphical user interface (GUI) library developed by Bill Spitzak and others. Made to accommodate 3D graphics programming, it has an interface to OpenGL, but it is also suitable for general GUI programming.
The tkinter package (“Tk interface”) is the standard Python interface to the Tcl/Tk GUI toolkit. Both Tk and tkinter are available on most Unix platforms, including macOS, as well as on Windows systems.
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Crazy Eddie's GUI (CEGUI) system is a graphical user interface C++ library. It was designed particularly for the needs of video games, but the library is usable for non-game tasks, such as applications and tools.
Nevron Open Vision for .NET is a suite of advanced UI components that helps you develop feature-rich Web (Blazor WebAssenbly) and Desktop (WinForms, WPF, Xamarin.Mac) applications from a single code base.
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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.
Create Tkinter interfaces easily using a Drag-And-Drop editor. Includes Button, Labels, Entry, CheckBox, Listbox.
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.
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