Authoring Tools Framework (ATF) is a set of C#/.NET components for making game development tools on Windows. ATF has been in development for over 8 years and has been used to make many custom tools such as Naughty Dog's level editor and shader editor for The Last of Us, Guerrilla Game's sequence editor for Killzone: Shadow Fall, an animation blending tool at Santa Monica Studios, a level editor at Bend Studio, a visual state machine editor for Quantic Dream, and many others. After many years of proprietary releases, ATF is now being released as an open source project on GitHub.