DEV.to - Where software engineers connect, build their resumes, and grow.
wxWidgets - wxWidgets: Cross-Platform GUI Library
Gila CMS - An on-in-one solution for the digital business
Electron - Build cross platform desktop apps with web technologies
WordPress - WordPress is web software you can use to create a beautiful website or blog. We like to say that WordPress is both free and priceless at the same time.
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.