Ext uses a Dual License business model for its software development libraries and offers licenses for two distinct purposes - commercial and open source development.

Quid Pro Quo

Dual Licensing is based on the principle of Quid Pro Quo - "something for something". In return for the advantages you realize from using an Ext product to create your application, we require that you do one of the following:

Contribute to the continued development of the product by purchasing commercial licenses from Ext. This option secures you the right to distribute your application under the license terms of your choice.
Contribute to the Open Source community by placing your application under an Open Source license (e.g. GPL v3). This option secures all users the rights to obtain the application's full source code, modify it, and redistribute it.

A Quick Overview

If you derive a commercial advantage by having a closed source solution, you must purchase an appropriate number of commercial licenses from Ext. By purchasing commercial licenses, you are no longer obligated to publish your source code.
If you wish to use the open source license of an Ext product, you must contribute all your source code to the open source community and you must give them the right to share it with everyone too.

Why Does Ext Use Dual Licensing?

Since its inception Ext has had a very active open source community and has reached its current maturity and stability with the help of a worldwide community of like-minded developers. We like being an active member of the open source community and we are dedicated to remaining involved.

By selling commercial licenses, we are able to staff a dedicated development team to ensure continued progress, quality enhancements and first-class technical support for developers using Ext products.