[slavik81]

The open source version of Qt is LGPL, which basically means you may use it in a proprietary application if you use dynamic linking. If you link statically or copy any of its code, then your program must be free software (GPL).

If you pay for a commercial license, you can link statically without restriction. The commercial version is also necessary for locked-down platforms like iOS where the dynamic linking can't be changed by the end user of the software.

IANAL, and there are a few details I glossed over, but that's the simple version.

[Nokinside]

Either dynamic linking or provide object files that can be linked with the library.

In essence, you can use it in proprietary application as long as you don't modify the library and you provide means to switch to different version of the library.

[hurd]

"If you link statically or copy any of its code, then your program must be free software (GPL)." I don't the first part is true (the second one is though).

https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDyn...

[slavik81]

The second part isn't technically true either. You can copy code without requiring a license if you meet the requirements for fair use. For example, copying function signatures for interoperability.

I was trying to be conservative and paint a simplified picture of the license that you can't go wrong by following, but I definitely erred in leaving out some possibilities and presenting it as if they don't exist.

[donatj]

If I statically link is my code inherintly LGPL or could I still license MIT?

[int_19h]

If LGPL was "viral" even when linking dynamically, there would be no point in it (it'd be like GPL).

So, yes. You can use MIT.

Of course, the dynamic dependency still remains LGPL.

[kuschku]

Yes and no. LGPL only is non-viral if the end user can trivially replace the linked library with their own version.