Sencha
Welcome to the Ext JS 4!
Ext JS 4 is a pure JavaScript application framework that works everywhere from IE6 to Chrome 11. It enables you to create the best cross-platform applications using nothing but a browser, and has a phenomenal API.
This is the biggest upgrade we've ever made to Ext JS and we think you're going to love it.
![](welcome/img/hero-extjs4-alt.png)
What’s New
We have also been posting summaries of new features and changes to our blog:
Upgrading
Sencha also offers training courses and professional services for companies wishing to use Ext JS 4.