[Interest] Licensing

Jérôme Godbout godboutj at amotus.ca
Sat Oct 5 19:19:01 CEST 2019

This is the true problem: when you need a lawyer, a sale rep and Qt support just to determine what you should do or buy, you know this is one hell of a brain f*** problem. I think Qt might just be missing sales because of this. Make it clear, make it obvious what people should buy or make a package with a displayed price point. I'm sure many just use Qt and try as hard as they can to be legit but at some point just gave up and say "screw this, let's use the free and hope nobody see it".

We want transparency on this matter one day. I have some project moving away of Qt  just because we are unsure if this a valid use case and the client doesn't have the time nor the resource for lawyer wasted money.

I hope one day Qt step up once and for all on this, the fact that this question rise over and over again is a huge indicator of the problem.

I really do like the Qt framework, but the licensing is a mine field.

From: Interest <interest-bounces at qt-project.org> on behalf of Giuseppe D'Angelo via Interest <interest at qt-project.org>
Sent: Saturday, October 5, 2019 12:16 PM
To: interest at qt-project.org <interest at qt-project.org>
Subject: Re: [Interest] Licensing


Il 05/10/19 13:17, Colin Worth ha scritto:
> My company has developed embedded and cross-platform GUI software using free open-source QT, the latest version. We are using the libraries that are included with the standard open-source installation. Soon we will freeze the version number, because we need to go through the FDA certification process. The software will be included with a medical device and we may also develop a sub-project that can be sold directly to consumers (its a medical device for amputees) Can someone briefly summarize our options as far as licensing (I have already read and googled many links, read through license terms, etc., even including a suggestion that we need to hire a lawyer, but this seems like a pretty straightforward question.)
> 1) Are we free to sell and distribute the software with our product, or as a download, as long as we dynamically link to the Qt libraries (as happens automatically when deploying with mac/windeployqt). Do we need to post any part of our source code online?

Unfortunately it IS a question for your own lawyers. The point is that
you need an authoritative answer from an IP specialist operating in your
country, with knowledge about your specific domain.

Note that you said "open source" Qt, which is meaningless -- different
parts of Qt are covered by different open source licensing schemes
(LGPL3, GPL2/3, LGPL2, ...), that carry very very very different
obligations. You need to audit your source and figure out which ones
you're actually using. The same thing applies for any other 3rd party
library you are using.

And while a license like LGPL3 doesn't mandate publishing the source
code of the application linked against a LGPL3 library, it *still* puts
further constraints on such an application, that may or may not be fine
with you.

There is a number of online videos that might help at getting a rough
idea about whether you'd be fine at using an open source license, but I
cannot stress this enough: they're *not* authoritative answers for your
*specific* case, and you shouldn't risk your entire business strategy
based on what a complete stranger said on the Internet!

> https://www.youtube.com/watch?v=bwTlCBbB3RY

> https://www.youtube.com/watch?v=lSYDWnsfWUk

> 2) If not, how much does commercial licensing cost, not for ongoing development, but just to include Qt with a product, or would that be determined on a case-by-case basis with the QT company.

The quotes are not public; this is a question for your own Qt Sales

Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - The Qt, C++ and OpenGL Experts

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