Glue42 - Integrate desktop and web applications to create a fluid user experience, synchronise data and trigger actions from any desktop or web application.
wxWidgets - wxWidgets: Cross-Platform GUI Library
OpenFin - Call Center Technology by OpenFin: Unified Workspace for Enhanced Productivity
Electron - Build cross platform desktop apps with web technologies
Quantrix - Quantrix is a business and financial modeling platform.
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.