wxWidgets - wxWidgets: Cross-Platform GUI Library
Linx - Integration and automation platform for growing businesses
Electron - Build cross platform desktop apps with web technologies
DHTMLX Suite - DHTMLX Suite offers JavaScript UI library for building cross-browser web and mobile applications.
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.
PHPmaker - PHPMaker is a powerful automation tool that can generate a full set of PHP quickly from MySQL, PostgreSQL, Oracle, Microsoft Access, Microsoft SQL Server and SQLite databases.