GTK topic
GTK (formerly GIMP ToolKit and GTK+) is a free software cross-platform widget toolkit for creating graphical user interfaces. It is licensed under the terms of the GNU Lesser General Public License, allowing both free and proprietary software to use it. It is one of the most popular toolkits for the Wayland and X11 windowing systems.
iridium
Native Linux IRC client built in Vala and Gtk for elementary OS
gsimplecal
Simple and lightweight GTK calendar (BSD license)
gnvim
GUI for neovim, without any web bloat
haki
Build native apps using GTK4 and a dialect of HTML, declarative format allows you to create advanced structures with ease.
gi-crystal
Tool to generate Crystal bindings for gobject-based libraries (i.e. GTK)
tijolo
Simple and fast keyboard focused IDE written in Crystal and GTK.
crystal-gobject
gobject-introspection for Crystal