wxWidgets - wxWidgets: Cross-Platform GUI Library
Oracle Mobile Application - Oracle Mobile Application framework or Oracle Mobile Application development platform is a hybrid mobile framework for rapidly developing single source applications for many platforms and devices.
Electron - Build cross platform desktop apps with web technologies
AppGyver Composer - Visual enterprise-grade low code mobile app builder
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.
Mendix - Mendix is the fastest and easiest low-code platform used by businesses to create and continuously improve mobile and web apps at scale.