Qt (cute) is a cross-platform application framework that is used for developing application software that can be run on various software and hardware. Developed by Qt Project
License: Open Source
GTK+ is primarily designed for Linux and GNOME applications, making it a lightweight option for simple applications, while Qt is a more robust, cross-platform toolkit suitable for complex UIs with extensive features and commercial support. Qt's performance and tools for UI design make it a preferred choice for larger, more intricate applications.