1. Nana C++ Library - a modern C++ GUI library

  2. GTK+ is a multi-platform toolkit for creating graphical user interfaces.

  3. Flowlab is an online game creator. Make your own games to share with friends.

    freemium $59.0 / Annually (Indie "Single user" "unlimited games" "native app exports")

  4. wxWidgets: Cross-Platform GUI Library

  5. JavaFX is the next step in the evolution of Java as a rich client platform.

  6. Make pixel art games in your browser

  7. Riverbank | Software | PyQt | What is PyQt?

  8. Flutter is Google’s mobile UI framework for crafting high-quality native experiences on iOS and Android in record time. Flutter works with existing code, is used by developers and organizations around the world, and is free and open source.

  9. Build cross platform desktop apps with web technologies

  10. Build cross-platform desktop applications with JavaScript🚀

  11. JUCE is a wide-ranging C++ class library for building rich cross-platform applications and plugins...

  12. Create cross-platform desktop apps in minutes, not months