Can we sell the Qt application developed under LGPLv3

dhu0504

I am using Qt to develop an application that run in the embedded device.
Can i sell my Qt application under LGPL for commercial products?

Please clarify the above.

sierdzio

@dhu0504 said in Can we sell the Qt application developed under LGPLv3:

I am using Qt to develop an application that run in the embedded device.
Can i sell my Qt application under LGPL for commercial products?

Please clarify the above.

LGPL and GPL licenses do not prohibit selling, reselling etc. You can sell your application.

However, make sure you don't break the license - with LGPL your customers have to have the ability to swap Qt version for their own. This is often impossible in embedded devices, thus LGPL gets violated.

Also, if you patch Qt, these patches should be made available to your customers as well.

dhu0504

Thank you for your reply.

I am Confusing the terms in the LGPLv3. Can you please explain about the terms of LGPLv3.

Is it possible to restrict the source code to the user using LGPLv3.

aha_1980

@dhu0504

Just an addition to @sierdzio: If you modify Qt, you must make the patches available.

For everything else: contact a lawyer to be on the safe side.

sierdzio

See the first dropdown at https://www.qt.io/download and more info at https://www.qt.io/faq/

Is it possible to restrict the source code to the user using LGPLv3.

You don't have to share your code with your customers under LGPLv3.

You do have to share Qt code, and any Qt patches you make, with your customers, upon request.

dhu0504

Thanks. Need one more clarification. I am using another third party source under GPL in the Qt application.

Can i sell this Qt app with LGPLv3 terms.

SGaist

@dhu0504 said in Can we sell the Qt application developed under LGPLv3:

Thanks. Need one more clarification. I am using another third party source under GPL in the Qt application.

Can i sell this Qt app with LGPLv3 terms.

Hi,

WARNING I'm not a lawyer.

No you can't, if you link to one GPL library in your application, then its protection covers the whole application. So you can still sell your application but only under GPL. Therefore if you want to keep LGPL for your application, you have to replace that GPL component with another one that has a licence compatible with LGPL.

sierdzio

@SGaist said in Can we sell the Qt application developed under LGPLv3:

Therefore if you want to keep LGPL for your application, you have to replace that GPL component with another one that has a licence compatible with LGPL.

Indeed. There is one more workaround for this: build a separate application out of that GPL library and then interact with it via command line, dbus, sockets etc. So that there is no direct linking.