TGUI is a cross-platform modern c++ GUI library.
Although TGUI was created for SFML, it now also has built-in backends for SDL and GLFW.
The gui is easy to use, with only a few lines you can e.g. have a fully functional TextBox on your screen. The widgets can be created by just using colors or by using images, making the look very customizable.
TGUI comes with its own Gui Builder, which allows designing your gui more easily. The widgets are loaded in your program by simple calling gui.loadWidgetsFromFile("form.txt").
TGUI will work on multiple platforms. Not only does it work on Windows, Linux and macOS, but also on Android and iOS. It has also been reported to work on Raspberry Pi and FreeBSD.
The core of TGUI and its widgets are independent from the rendering, only the backend depends on external libraries.
Each backend itself is also divided in three reusable components: event input, font loading and rendering. The SFML_OPENGL3 and GLFW_OPENGL3 backends for example share their rendering and font loading code. Custom backends can thus also reuse parts of existing backends.