QCAD License

Starting with version 3.1, the QCAD source code is distributed under the open source license GPLv3 with exceptions to allow proprietary extensions.

The QCAD source code also contains 3rd party libraries and various resources which are distributed under their respective licenses. For a complete overview of the various licenses involved, please refer to the LICENSE.txt file.

In all source code distributions of QCAD, you can also find a copy of the GPLv3 and the exceptions for plugins and add-ons.

GPLv3

The GNU General Public License (GNU GPL or GPL) is the most widely used free software license. It guarantees end users (individuals, organizations, companies) the freedoms to use, study, share (copy), and modify the software. Modifications and additions made to the software must generally be distributed under the same license.

GPLv3 Exceptions

QCAD is distributed with an optional set of exceptions which extend the freedoms granted by the GPLv3.

These exceptions allow us as well as any other organizations and individuals to distribute commercial, proprietary plugins or scripts together with the open source QCAD package.

As an example, we distribute a package called 'QCAD Professional' which contains the QCAD application under GPLv3, bundled together with proprietary extensions:

  • Additional, proprietary, closed-source tools which are only available in QCAD Professional
  • DWG read/write support and extended DXF read/write support through the proprietary OpenDesign Teigha libraries

Extending QCAD

To develop commercial, proprietary plugins or script add-ons for QCAD, you don't require any special developer license. Your plugins and add-ons may be distributed together with QCAD, under any license you choose (see GPLv3 exceptions). You may for example distribute the open source portion of QCAD (under GPLv3), together with your own, proprietary plugins for a license fee of your choice. Such a package must contain the GPLv3 license file as well as the GPLv3 exceptions file. 

Any modifications and additions which are made to the QCAD source code itself may only be redistributed under the GPLv3 with exceptions. Note that such direct modifications are usually not necessary, since almost all aspects and tools of QCAD can be easily extended or modified through plugins and script add-ons.

However, if you for example discover and fix a bug in the QCAD source code or port the QCAD source code to a new platform, those changes must be distributed under the GPLv3 (optionally with exceptions).

Extending and Distributing QCAD Professional

If you wish to base your plugin, add-on or an entirely new product on QCAD Professional or you wish to include the QCAD Professional extensions in the new package you sell or distribute, you can do so with a QCAD C++ Libraries license. QCAD Professional contains proprietary professional tools, DWG support and extended DXF support. A detailed list of all features is available on our web site at: http://qcad.org/en/qcad-documentation/qcad-features. Features provided by QCAD Professional extensions are highlighted in italic.

A QCAD C++ Libraries license gives you (in addition to the above) access to the source code of our proprietary plugins and script add-ons (QCAD Professional tools, Teigha DXF/DWG plugin) under the QCAD Libraries license agreement.

DXF/DWG Support

The QCAD Teigha plugin sources for DXF/DWG support may be used to compile your own plugin with your own Teigha license or the plugin may be used and redistributed as pre-compiled plugin provided by us (Windows, Mac OS X, Linux 32bit and Linux 64bit). If you only need basic DXF support, you may alternatively use the dxflib library which is also included as part of the QCAD C++ Libraries license.

Royalties

If your end product is essentially QCAD Professional with your own extensions, you have to purchase licenses from us for resale. In that case, you are becoming a reseller of QCAD Professional and purchase the number of licenses required from us with a reseller discount of typically 25%.

If your end product is significantly different from QCAD Professional, you may distribute the end product under your own license terms, royalty-free. This is for example the case for a command line tool or an application that only uses the graphics views and DXF/DWG support of QCAD Professional but not the typical QCAD Professional user interface and tools.

You can also choose to distribute your plugins and script add-ons as a separate product without QCAD and leave it up to the user to purchase and maintain their respective QCAD licenses. In that case, no royalties are required to be payed to RibbonSoft.

Product Name

An end product that consists of QCAD and proprietary plugins or script add-ons must not be distributed under the name 'QCAD' or 'QCAD Professional'. Instead, you can choose your own product name. You may mention in the product documentation or about dialog that your product uses QCAD technology.