Before you begin, make the right license choice.
Qt is a commercial and open source licensed product developed by The Qt Company, a solely owned entity of Digia Plc, together with the Qt Project under the open source governance model.
A financial backbone is needed to keep Qt development, testing, packaging, releasing, worldwide availability and ultimately, Qt’s greatness, ticking. Over three quarters of the Qt code is written by employees of The Qt Company and through the sale of commercial licenses Qt is kept on its feet.
We believe in giving choice and freedom to developers and companies by offering different licensing options that support a wide variety of product strategies. The result of this is our dual-licensing model – open source and commercial. We want to help you find the license that is right for 1) your development requirements and 2) your deployment needs.
When developing with Qt under the LGPL, we stress that you are aware of all the obligations that must be legally complied with. Please make sure you are informed about the obligations of the LGPL before you start developing.
We have also developed an FAQ about developing with the LGPL that should address most of your questions.
If you are developing a Qt-based device, a commercial license is recommended to embed and control Qt on your device. A commercial license allows you to, for example, control your device’s user experience, build proprietary functionality on top of Qt and to lock down your device to create your own developer ecosystem. A commercial license from The Qt Company keeps your code proprietary where only you can control and monetize on your end product’s development, user experience and distribution.
If you do not want to share your code, leave your device “open” for external developers to alter or update your device’s functionality, you cannot use the open source licenses* for device creation with Qt.
* LGPLv2.1, LGPLv3 or GPL v3 and some modules under LGPLv3 only
Qt has been created under the belief of open development and providing freedom and choice to developers. You may opt for a full-featured Qt development experience available from The Qt Company’s commercial license or you may opt for open source use of Qt where some features and modules are available under LGPLv2.1, LGPLv3 or GPL v3 and some under LGPLv3 only. What it comes down to is determining your needs
Depending on your development and distribution requirements, you may want to choose a commercial license for additional functionality, world-class support and a close strategic relationship with The Qt Company to make sure your product and development goals are met. Get an overview of the differences here ›
In order to preserve the true meaning of open development and uphold the spirit of free software, it is imperative that the rules and regulations of open source licenses required by the Free Software Foundation are followed. Learn more: http://www.gnu.org/licenses.
When deciding which license to use, please check your corporate open source policy or consult a SW licensing legal expert.