The Haiku operating system uses an extended and modernised version of the Be API that was used by its predecessor BeOS. Haiku Inc. is expected to drop binary and source compatibility with BeOS at some future time, which will result in a Haiku API.
As a separate layer on top of the operating system
The X Window System contains primitive building blocks, called Xt or "Intrinsics", but they are mostly only used by older toolkits such as: OLIT, Motif and Xaw. Most contemporary toolkits, such as GTK or Qt, bypass them and use Xlib or XCB directly.
The Amiga OSIntuition was formerly present in the Amiga Kickstart ROM and integrated itself with a medium-high level widget library which invoked the Workbench Amiga native GUI. Since Amiga OS 2.0, Intuition.library became disk based and object oriented. Also Workbench.library and Icon.library became disk based, and could be replaced with similar third-party solutions.
Since 2005, Microsoft has taken the graphics system out of Windows' kernel.[2]
BOOPSI (Basic Object Oriented Programming System for Intuition) was introduced with OS 2.0 and enhanced Intuition with a system of classes in which every class represents a single widget or describes an interface event. This led to an evolution in which third-party developers each realised their own personal systems of classes.
MUI: object-oriented GUI toolkit and the official toolkit for MorphOS.
ReAction: object-oriented GUI toolkit and the official toolkit for AmigaOS.
Cocoa - used in macOS(see also Aqua). As a result of macOS' OPENSTEP lineage, Cocoa also supports Windows, although it is not publicly advertised as such. It is generally unavailable for use by third-party developers.[citation needed] An outdated and feature-limited open-source subset of Cocoa exists within the WebKit project, however; it is used to render Aqua natively in Safari (web browser) for Windows.[citation needed] Apple's iTunes, which supports both GDI and WPF, includes a mostly complete binary version of the framework as "Apple Application Support".[citation needed]
The Visual Component Library (VCL) is Embarcadero's toolkit used in C++Builder and Delphi. It wraps the native Windows controls, providing object-oriented classes and visual design, although also allowing access to the underlying handles and other WinAPI details if required. It was originally implemented as a successor to OWL, skipping the OWL/MFC style of UI creation, which by the mid-nineties was a dated design model.[3]
Windows Forms (WinForms) is Microsoft's .NET set of classes that handle GUI controls. In the cross-platform Mono implementation, it is an independent toolkit, implemented entirely in managed code (not wrapping the Windows API, which doesn't exist on other platforms).[4] WinForms' design closely mimics that of the VCL.
Note that the X Window System was originally primarily for Unix-like operating systems, but it now runs on Microsoft Windows as well using, for example, Cygwin, so some or all of these toolkits can also be used under Windows.
GTK, open source (LGPL), primarily for the X Window System, ported to and emulated under other platforms; used in the GNOME, Rox, LXDE and Xfce desktop environments. The Windows port has support for native widgets.
IUP, open source (MIT), a minimalist GUI toolkit in ANSI C for Windows, UNIX and Linux.
Tk, open source (BSD-style), a widget set accessed from Tcl and other high-level script languages (interfaced in Python as Tkinter).
Based on C++ (including bindings to other languages)
CEGUI, open source (MIT License), cross-platform widget toolkit designed for gamedevelopment, but also usable for applications and tool development. Supports multiple renderers and optional libraries.
FLTK, open source (LGPL), cross-platform toolkit designed to be small and fast.
Juce provides GUI and widget set with the same look and feel in Microsoft Windows, X Windows Systems, macOS and Android. Rendering can be based on OpenGL.
Qt, proprietary and open source (GPL, LGPL) available under Unix and Linux (with X11 or Wayland), Windows (Desktop, CE and Phone 8), macOS, iOS, Android, BlackBerry 10 and embedded Linux; used in the KDE, Trinity, LXQt, and Lumina desktop environment, it's also used in Ubuntu's Unity shell.
Rogue Wave Views (formerly ILOG Views) provides GUI and graphic library for Windows and the main X11 platforms.
Tkinter, open source (BSD) is a Python binding to the Tk GUI toolkit. Tkinter is included with standard GNU/Linux, Microsoft Windows and macOS installs of Python.
Kivy, open source (MIT) is a modern library for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps. Fully written in Python with additional speed ups in Cython.
PySide, open source (LGPL) is a Python binding of the cross-platform GUI toolkit Qt developed by The Qt Company, as part of the Qt for Python project.
PyQt, open source (GPL and commercial) is another Python binding of the cross-platform GUI toolkit Qt developed by Riverbank Computing.
PyGTK, open source (LGPL) is a set of Python wrappers for the GTK graphical user interface library.
Fyne, open source (BSD) is inspired by the principles of Material Design to create applications that look and behave consistently across Windows, macOS, Linux, BSD, Android and iOS.
The Abstract Window Toolkit (AWT) is Sun Microsystems' original widget toolkit for Java applications. It typically uses another toolkit on each platform on which it runs.
Swing is a richer widget toolkit supported since J2SE 1.2 as a replacement for AWT widgets. Swing is a lightweight toolkit, meaning it does not rely on native widgets.
Apache Pivot is an open-source platform for building rich web applications in Java or any JVM-compatible language, and relies on the WTK widget toolkit.
The Standard Widget Toolkit (SWT) is a native widget toolkit for Java that was developed as part of the Eclipse project. SWT uses a standard toolkit for the running platform (such as the Windows API, macOS Cocoa, or GTK) underneath.
Codename One originally designed as a cross platform mobile toolkit it later expanded to support desktop applications both through JavaSE and via a JavaScript pipeline through browsers
java-gnome provides bindings to the GTK toolkit and other libraries of the GNOME desktop environment
Qt Jambi, the official Java binding to Qt from Trolltech. The commercial support and development has stopped[5]
FireMonkey or FMX is a cross-platform widget and graphics library distributed with Delphi and C++Builder since version XE2 in 2011. It has bindings for C++ through C++Builder, and supports Windows, macOS, iOS, Android, and most recently Linux. FireMonkey supports platform-native widgets, such as a native edit control, and custom widgets that are styled to look native on a target operating system. Its graphics are GPU-accelerated and it supports styling, and mixing its own implementation controls with native system controls, which lets apps use native behaviour where it's important (for example, for IME text input.)
IP Pascal uses a graphics library built on top of standard language constructs. Also unusual for being a procedural toolkit that is cross-platform (no callbacks or other tricks), and is completely upward compatible with standard serial input and output paradigms. Completely standard programs with serial output can be run and extended with graphical constructs.
fpGUI is created with the Free Pascal compiler. It doesn't rely on any large 3rdParty libraries and currently runs on Linux, Windows, Windows CE, and Mac (via X11). A Carbon (macOS) port is underway.
CLX (Component Library for Cross-platform) was used with Borland's (now Embarcadero's) Delphi, C++ Builder, and Kylix, for producing cross-platform applications between Windows and Linux. It was based on Qt, wrapped in such a way that its programming interface was similar to that of the VCL toolkit. It is no longer maintained and distributed, and has been replaced with FireMonkey, a newer toolkit also supporting more platforms, since 2011.
^Migrating to client-side windowsArchived 27 April 2011 at the Wayback Machine: "GDK looks for the GDK_NATIVE_WINDOWS environment variable and makes all windows native if it is set. It also tries to be more compatible with the way prior versions worked in some other ways."
^Coding Horror: Non-Native UI Sucks: "[…] has a cross-platform UI based on GTK, which produces predictably bland, least-common-denominator results:"
^WxWidgets Compared To Other Toolkits: "Qt doesn't have true native ports like wxWidgets does. Qt does not use system provided widgets, but emulates it with themes. What we mean by this is that even though Qt draws them quite realistically, Qt draws its own widgets on each platform."
^"Qt Modular Class Library". Digia. Archived from the original on 1 November 2013. Qt uses the native graphics APIs of each platform it supports, taking full advantage of system resources and ensuring that applications have native look and feel.
^"The Qt 4 Style API". The Qt Company. Qt's built-in widgets use [QStyle] to perform nearly all of their drawing, ensuring that they look exactly like the equivalent native widgets.
