FlexBuilder: the best UI framework for Unity3D

For more details, see the Detailed Features page.

Comparison with Unity built-in frameworks

Unity built-in
Unity's built-in UI system
Works with all AssetStore assets
Works with all existing scripts/code
Live-editing in-game/editor
Unity built-in
Experimental, 'not production ready'
Implements less than 90% of the CSS3/Flexbox spec
No live-editing
No integration with last 10 years of Unity UI scripts and assets
Slow to build/edit
Fast when not changing
Visual UI editor (buggy)