wxWidgets - wxWidgets: Cross-Platform GUI Library
PHPRunner - PHPRunner builds visually appealing web interface for popular databases.
Electron - Build cross platform desktop apps with web technologies
Scriptcase - Powerful web low-code RAD platform. Unleash the power of web development and boost your productivity time creating delightful projects with magnificent BI solutions.
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.
AdminLTE - Web-based admin dashboard & control panel template. Highly customizable and easy to use.