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Contribution via Open Source
When selecting an open source license for your project, you contribute to free and open source software development by using Qt under any of the following licenses: LGPL version 3, GPL version 2 and GPL version 3.
Basic Premises of the Qt Open Source Model
GPL – All users have the rights to obtain, modify and redistribute the full source code of your application. Your users are granted rights founded on the four freedoms of the GNU General Public License.
LGPL – Any modification to a Qt component covered by the GNU Lesser General Public License must be contributed back to the community. This is the primary open source Qt license, which covers the majority of Qt modules.
Please note that there are parts of Qt that are only provided under GPL for open source users that will require you to license your application under a GPL compatible license. Qt also ships with third party open source components that might require respective licensing compliancy, if used. See details of other licenses inside Qt .
Check out which components are available under the different open source models in the Qt Product Map.
Open Source Usage Obligations
The majority of the Qt modules are available under the LGPL v3 and GPL v3 open source license. When developing under this license your obligations are to:
- Provide a re-linking mechanism for Qt libraries
- Provide a license copy & explicitly acknowledge Qt use
- Make a Qt source code copy available for customers
- Accept that Qt source code modifications are non-proprietary
- Make “open” consumer devices
- Accept Digital Rights Management terms, please see the GPL FAQ
- Take special consideration when attempting to enforce software patents FAQ
If the open source license model isn't the right fit for your project or you have concerns about being able to comply to the license terms, contact us. We can help you secure rights to develop, use and distribute your application under a choice of commercial license packages.
