5 ms·

How viable is LGPL'd Qt, in its current situation, for closed-source desktop applications?

by obdev 4y ago

nu11ptr 4y ago
As long as you dynamically link and don't use the non-free components (charts, etc.), I think it would be just fine for a C++ or Python app. However, personally, I am leaning towards Flutter atm. They have decent emulated native looking controls for Windows/Mac, seems to have a strong cross platform focus, strong Rust integration via a bridge library, and has a better license with good free charting options.
dark-star 4y ago
You will be missing a few modules/plugins/tools which are commercial-only (I cannot seem to find the actual list right now though) but other than that, the LGPL was made exactly for that reason to allow linking an open-source library (Qt) into a closed-source program. As long as you don't modify the Qt source (or you modify and re-distribute it per LGPL) you should be safe (IANAL obviously)
detaro 4y ago
Very. That's almost the point of LGPL.
nottorp 4y ago
Can you afford a lawyer on retainer?
- stjohnswarts 4y ago
  What? It's doesn't take a genius to understand it. They clearly label what is and what is not LGPL. It doesn't hurt to double check the source files of course and have redundant confirmation. You don't need a lawyer for everything in life.
  - nottorp 4y ago
    I don't need a lawyer to use a LGPL lib. Considering how many threats you have to go through to get the LGPL version, I need one because Digia is likely to disagree with my interpretation.
    - stjohnswarts 4y ago
      Please refer us to court cases where they went after people and made false claims. Until then I think I'll keep Qt in my belt of tools.
- LtWorf 4y ago
  Just so you know, webkit is LGPL, because it got forked from KDE (KHTML).
didgetmaster 4y ago
I have a project I built using Qt version 5. It seems to work pretty well. I didn't upgrade to version 6 because it was initially missing some modules I was using, but it sounds like they have now ported those to their version 6 code. When I get some cycles, I will have to look into upgrading.
- yellow_lead 4y ago
  Check out qt5compat module :)
samsaga2 4y ago
The LGPL license allows you to make closed applications without problems if you comply with the rules. But the Qt guys will call you and make threats (very nicely). Real case.
seego 4y ago
See https://doc.qt.io/qt-6/qtmodules.html#gpl-licensed-addons https://doc.qt.io/qt-6/qtmodules.html#gpl-licensed-addons for the few GPL/commercial only modules
stagger87 4y ago
Super viable. I'm aware of several companies using the LGPL license for their closed source desktop applications, including my own. Don't let the other replies scare you. No one will call and threaten you and you don't need a lawyer. For cross platform native desktop applications, Qt is far and away the best option. QtCreator is pretty awesome too.

How viable is LGPL'd Qt, in its current situation, for closed-source desktop applications?

by obdev 4y ago

How viable is LGPL'd Qt, in its current situation, for closed-source desktop applications?

As long as you dynamically link and don't use the non-free components (charts, etc.), I think it would be just fine for a C++ or Python app. However, personally, I am leaning towards Flutter atm. They have decent emulated native looking controls for Windows/Mac, seems to have a strong cross platform focus, strong Rust integration via a bridge library, and has a better license with good free charting options.

dark-star 4y ago

You will be missing a few modules/plugins/tools which are commercial-only (I cannot seem to find the actual list right now though) but other than that, the LGPL was made exactly for that reason to allow linking an open-source library (Qt) into a closed-source program. As long as you don't modify the Qt source (or you modify and re-distribute it per LGPL) you should be safe (IANAL obviously)

detaro 4y ago

Very. That's almost the point of LGPL.

nottorp 4y ago

Can you afford a lawyer on retainer?

stjohnswarts 4y ago
What? It's doesn't take a genius to understand it. They clearly label what is and what is not LGPL. It doesn't hurt to double check the source files of course and have redundant confirmation. You don't need a lawyer for everything in life.
- nottorp 4y ago
  I don't need a lawyer to use a LGPL lib. Considering how many threats you have to go through to get the LGPL version, I need one because Digia is likely to disagree with my interpretation.
  - stjohnswarts 4y ago
    Please refer us to court cases where they went after people and made false claims. Until then I think I'll keep Qt in my belt of tools.
LtWorf 4y ago
Just so you know, webkit is LGPL, because it got forked from KDE (KHTML).

didgetmaster 4y ago

I have a project I built using Qt version 5. It seems to work pretty well. I didn't upgrade to version 6 because it was initially missing some modules I was using, but it sounds like they have now ported those to their version 6 code. When I get some cycles, I will have to look into upgrading.

yellow_lead 4y ago
Check out qt5compat module :)

samsaga2 4y ago

The LGPL license allows you to make closed applications without problems if you comply with the rules. But the Qt guys will call you and make threats (very nicely). Real case.

seego 4y ago

See https://doc.qt.io/qt-6/qtmodules.html#gpl-licensed-addons https://doc.qt.io/qt-6/qtmodules.html#gpl-licensed-addons for the few GPL/commercial only modules

stagger87 4y ago

Super viable. I'm aware of several companies using the LGPL license for their closed source desktop applications, including my own. Don't let the other replies scare you. No one will call and threaten you and you don't need a lawyer. For cross platform native desktop applications, Qt is far and away the best option. QtCreator is pretty awesome too.