Slint is described as 'GUI toolkit for Rust, C++, and JavaScript to efficiently develop fluid graphical user interfaces for embedded devices and desktop applications' and is a software framework in the development category. There are more than 10 alternatives to Slint for a variety of platforms, including Linux, Windows, Mac, Self-Hosted and BSD apps. The best Slint alternative is Qt, which is both free and Open Source. Other great apps like Slint are Electron, Flutter, React Native and GTK.
Dear ImGui is a bloat-free graphical user interface library for C++. It outputs optimized vertex buffers that you can render anytime in your 3D-pipeline enabled application. It is fast, portable, renderer agnostic and self-contained (no external dependencies).
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.
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...
Felgo is a Cross-Platform Development SDK based on the popular Qt framework. Felgo Apps and Games are created within the Qt Creator.
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CopperSpice is a set of individual libraries which can be used to develop cross platform software applications in C++. It is a totally open source project released under the LGPL V2.1 license and was initially derived from the Qt framework.
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.
Repose is a Rust UI framework with a Compose-like programming model. It's organized as a small core (repose-core) plus higher-level UI/layout (repose-ui) and platform runners (repose-platform) that currently target desktop (winit) and Android, with web support.
