Earcon ADF has two licensing options. No matter which license you choose, the overall business benefit of Zope + ADF is a dramatically lower total cost of ownership.

The guiding business principle of ADF is one of fair exchange, or Quid pro Quo ("something for something"). From a licensing perspective, we have two different products depending on usage and distribution, though technically they have the same source code.

Thanks to our licensing model, we are capable of producing superior software at a much lower cost than proprietary software vendors. Our licensing options include:

• The Commercial License, which allows you to provide commercial software licenses to your customers or distribute ADF-based applications within your organization. This is for organizations that do not want to release the source code for their applications as open source / free software; in other words they do not want to comply with the GNU General Public License (GPL). If you want more information on pricing, click here.
• For those developing open source applications, the Open Source License allows you to offer your software under an open source / free software license to all who wish to use, modify, and distribute it freely. The Open Source License allows you to use the software at no charge under the condition that if you use ADF in an application you redistribute, the complete source code for your application must be available and freely redistributable under reasonable conditions. Earcon bases its interpretation of the GPL on the Free Software Foundation's Frequently Asked Questions. For more information on ADF's Open Source License, click here.

At Earcon, we believe in open source / free software and we welcome all initiatives to publish more software under the GPL license, just as we have done.

In their simplest form, the following are general licensing guidelines:

• If your software is licensed under either the GPL-compatible Free Software License as defined by the Free Software Foundation or approved by OSI, then use our GPL licensed version.
• If you distribute a proprietary application in any way, and you are not licensing and distributing your source code under GPL, you need to purchase a commercial license of ADF
• If you are unsure, we recommend that you buy our cost effective commercial licenses. That is the safest solution. Licensing questions can be directed to licensing@earcon.com for our advice, and we encourage you to refer to the Free Software Foundation or a lawyer as appropriate.
• Commercially licensed customers get commercially supported product with assurances from ADF. Commercially licensed users are also free from the requirement of making their own application open source.

For OEM's, ISVs, corporate, and government users, a commercial license is the proper solution because it provides you with assurance from the vendor and releases you from the strict requirements of the GPL license.

Nevertheless, you can test ADF under the GPL license and inspect the source code before you purchase a commercial non-GPL license.