GTK Documentation

User interface


GTK is the primary library used to construct user interfaces. It provides user interface controls and signal callbacks to respond to user actions.

GTK API reference


An intermediate layer which provides a rendering API implemented using Cairo, OpenGL or Vulkan.

GSK API reference


An intermediate layer which isolates GTK from the details of the windowing system.

GDK API reference


Pango is the core text and font handling library used in GTK applications. It has extensive support for the different writing systems used throughout the world.

Pango API reference


GdkPixbuf is a library for image loading and manipulation.

GdkPixbuf API reference


Cairo is a 2D graphics library with support for multiple output devices. It is designed to produce consistent, high quality output on all media.

Cairo API reference

Core libraries


GLib provides the core application building blocks for libraries and applications written in C. It provides common data types used in GTK, the main loop implementation, and a large set of utility functions for strings and general portability across different platforms.

GLib API reference

GLib Unix-specific API reference

GLib Windows-specific API reference


GObject provides the object system used by GTK.

GObject API reference


GIO provides a portable, modern and easy-to-use file system abstraction API for accessing local and remote files; a set of low and high level abstractions over the DBus IPC specification; an application settings API; portable networking abstractions; and additional utilities for writing asynchronous operations without blocking the user interface of your application.

GIO API reference

GIO Unix-specific API reference

GIO Windows-specific API reference


GIRepository provides access to introspected API bindings built using gobject-introspection.

GIRepository API reference

Older versions


The GTK 3 toolkit.

GTK 3 API reference


The GTK 3 windowing system abstraction.

GDK 3 API reference


The accessibility toolkit, used by GTK 3.

ATK API reference