Dual Licensing


Dual Licensing is based on the principle of Give-and-take: in return for the advantages you realize from using VMime 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 VMime. This option secures you the right to distribute your application under the license terms of your choice.
  • Contribute to the Open Source community by releasing your application under the GNU GPL license. This option secures all users the rights to obtain the application’s full source code, modify it, and redistribute it.

What license is right for me?

If you derive a commercial advantage by having a closed source solution, you must purchase an appropriate number of commercial licenses for VMime. By purchasing commercial licenses, you are no longer obligated to publish your source code. However, you are required to publish any change made to the VMime codebase (ie. files included in the VMime distribution package) and give everyone the right to use and share it.

If you wish to use the Open Source license of VMime, you must contribute all your source code to the Open Source community (ie. release your code under the GNU GPL license) and you must give them the right to share it with everyone too. To know more about GPL compliance, please read the Practical Guide to GPL Compliance.

Learn more about VMime licenses…

Licensing Overview

VMime has two licensing options available. For more information about why these licenses were chosen, please visit the Dual Licensing Model page.

License Comparison Chart

Commercial version
Buy Online
GPL version
License cost License fee charged Free
Must provide source code changes to VMime Modified source code of VMime must be provided
Can create proprietary applications Yes, in accordance with the GNU LGPL v3 terms and exceptions for VMime
(see below)
No, applications are subject to the GPL and source code must be made available
Updates provided
Yes, freely distributed on this site
Support Not guaranteed
Number of developers One, Five or Unlimited, depending on the license
(see below)

Open Source License (GNU GPL)

We are supporters of Free and Open Source software (FOSS). This is the appropriate option if you are creating an Open Source application with a license compatible with the GNU GPL version 3. This license is free of charge.

We are currently working on an Open Source License Exception for FOSS Applications which are released under licenses which are not compatible with GNU GPL v3.

Commercial License

This is the appropriate option if you are creating proprietary applications which use VMime and do not want to distribute and share the source code of your application under the GNU GPL license.

The VMime commercial license actually is the GNU Lesser GPL license with the following exceptions:

  • You may link, statically or dynamically, your application with VMime, and you may distribute the resulting combined work under terms of your choice, without any of the additional requirements listed in clause 6 of the GNU Lesser General Public License;
  • You must either 1) purchase a Single Developer License for each developer who uses VMime in your company, or 2) purchase a Five Developers License if you have at most 5 developers who use VMime in your company, or 3) purchase an Unlimited Developers License;
  • You may NOT relicense the VMime code or grant the rights to anyone;
  • The license is not transferable, directly, indirectly or through a sale/merge/etc.

This license does not require your application to be GPL-compatible (ie: you are NOT forced to release your source code under the GNU (L)GPL v3 license), nor to touch anything to your application or your license: you may link your proprietary application against VMime library without sharing your source code.

Commercial licenses:

  • Are royalty-free;
  • Remove any obligations to release your source code under the GNU GPL; however, any change made to the VMime codebase should be published and brought back to the community (as with the GNU Lesser GPL license);
  • Are perpetual and include all public upgrades that are released after the date of purchase, for lifetime;
  • Are on a per developer basis. In your company, each person who works on an application, module or user interface which makes use of one or more VMime components is considered a developer, and requires to purchase one commercial licence.

You can purchase a commercial license online:


If you are not sure what license to use, or if you have any question about VMime licensing, please feel free to contact us.

Please note: individual technical assistance or custom support is not included with Commercial License. If you are looking for Premium individual support (quick and guaranteed answer, custom feature development…), please contact us (additional fees apply).

GPL v3 and dual-licensing

Hi all!

VMime has been relicensed under the GNU General Public License version 3. So, this will be the default license starting from version 0.9.1 (which is currently in development).

Additionally, due to a lot of demand, and to support development, VMime is now available under dual-licensing:

  • GNU GPL v3 for Free and Open Source projects. This is the default license for VMime.
  • Commercial license, for proprietary software. This license is available for purchase.

Please consult Licensing Overview and Dual-Licensing Model for more information about this.