Monday, 20 October 2014

Qt Creator Tutorial Z1 - Licenses

Warning: This just a briefing. If you want legal advice consult a real lawyer. Qt trademark belongs to Digia.


Licenses

Qt and Qt's libraries have few licenses. This might help you decide which license to use.

GPLv3
GNU General Public License v3 by Free Software Foundation. The flagship Free Software Foundation license for free software.

Advantages:
Free(cost)
Do almost anything to the source code
Sell source code or binaries
Modify source code or binaries

Disadvantages:
Must release source code for anything that uses the source code 
Any statically or dynamically linked software must be under GPLv3


LGPLv2.1
GNU Lesser General Public License v2.1 by FSF. Similar to GPLv3. However, LGPLv2.1 allows dynamic linking(e.g Qt libraries) .

Advantages:
Free(cost)
Do almost anything to the source code
Sell source code or binaries
Modify source code or binaries
Dynamically link software(e.g Qt libraries) without needing to use LGPLv2.1

Disadvantages:
Must release source code for anything that is statically compiled to it
Any statically software must be under LGPLv2.1

Digia Qt LGPL Exception version 1.1
Similar to LGPLv2.1. However, you can statically link software to other software if you don't modify the source code.

Advantages:
Free(cost)
Do almost anything to the source code
Sell source code or binaries
Modify source code or binaries
Dynamically and statically link software(e.g Qt libraries) without needing to change licenses if you don't modify source code

Disadvantages:
Must release source code if statically link and modify source code

Qt Commercial License
Qt Commercial License by Digia. Allows creation of proprietary or non-free software with Qt. Offered along with Qt support services.

Advantages:


Sell binaries without restriction


Modify source code without restriction

Disadvantages:
Costs money


For more information consult Qt's wiki.


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