NGUI (Next-Gen UI) is a UI system for the Unity Engine, first released back in 2011, long before Unity created their own UI system. NGUI became extremely popular shortly after its launch, derailing my plan to get started as an independent game developer. It also ended up being the starting point for Unity's own UI system. As of this writing (year 2025), it's still backwards compatible with projects created over a decade ago -- and I am using it in all of my own projects.

As of October 2025, NGUI is now completely free and open source. Feel free to use its code as you see fit -- but if you make your own UI system for some other engine using NGUI's code as the starting point, a thank you would be appreciated. :)

-Michael "Aren" Lyashenko