wxWidgets - wxWidgets: Cross-Platform GUI Library
Netbeans - NetBeans IDE 7.0. Develop desktop, mobile and web applications with Java, PHP, C/C++ and more. Runs on Windows, Linux, Mac OS X and Solaris. NetBeans IDE is open-source and free.
Electron - Build cross platform desktop apps with web technologies
C4droid - C4droid is an intelligent IDE and C/C++ compiler, allowing you to create your own application on Android devices.
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.
Orwell Dev-C - The official site of the Bloodshed Dev-C++ update, which is fully portable, and optionally ships with a 64bit compiler.