Ext JS - cross-browser JavaScript library

Ext JS is a cross-browser JavaScript library for building rich internet applications.

• High performance, customizable UI widgets
• Well designed, documented and extensible Component model
• Commercial and Open Source licenses available

Ext JS supports all major web browsers including:

• Internet Explorer 6+
• FireFox 1.5+ (PC, Mac)
• Safari 3+
• Opera 9+ (PC, Mac)

For download and more info click here