[rrgok]

Everytime a QT post comes someone bitch about the licensing model. And every time I google and try understand what is wrong with the licensing model. And everytime I end up confused about it.

Could you kindly ELI5 me what is wrong with QT licensing model?

[bradfa]

Qt (the company) releases MOST of their code under open source licenses, but not all. Qt4 was LGPLv2.1, Qt5 and beyond are under LGPLv3.

In every major Qt release, there's a handful of super useful but kind of niche widgets which aren't released under open source licenses, presumably as a sales tactic as buying licenses gets you these widgets and sometimes that is cheaper than building them yourself, but unless you need these, you probably don't care about this.

Although my experience attempting to buy licenses from Qt is about a decade out of date now, the way it roughly worked was you paid a per-seat-per-year fee to get a developer license or build-machine license. Then you bought bundles of deployment licenses, and the bigger the bundle then the lower the cost per license. If you are buying a bundle of a few thousand devices then you pay more per license than if you're buying a bundle of a few million. Either way, it is a significant chunk of cash you have to front to get your block of licenses and normally embedded projects are EXTREMELY sensitive to per-unit costs.

[seba_dos1]

Nothing's wrong with their licensing model, but they've been known for misrepresenting their licensing model in order to steer people towards their commercial offerings.

[bobmcnamara]

> And every time I google and try understand what is wrong with the licensing model. And everytime I end up confused about it. Could you kindly ELI5 me what is wrong with QT licensing model?

This right here! We customers and users alike are often confused by QTs piecemeal licensing model.

[freedomben]

I could be misunderstanding, but my read of the GP is that they aren't confused about the licensing model, they're confused by the hate for it

[rcxdude]

A big one that I've heard, is that they are funny about you developing with it under an open source license and then buying a commercial license. I.e. if you would potentially want to use something that's under the commercial license then you need to buy it when you start development instead of when you find you want the commercial side. I don't know if this is still the case, though.

[markfeathers]

From my perspective they spread FUD about open source licensing. QT core is LGPL3. Many applications would be fine with using LGPL3 in commercial applications. Read QT's landing page on licensing, and fossa has a good block post on requirements.

https://www.qt.io/qt-licensing

https://fossa.com/blog/open-source-software-licenses-101-lgp...

>And everytime I end up confused about it.

I think this is the point. If you're making a real application you may pay for the licensing to avoid the uncertainty/risk.

[pjmlp]

Some people don't like to pay for the work of others, while expecting to be paid for their own work.

Qt licensing is rather easy to understand.

Don't want to pay Qt? Then get the same money yourself, zero.

Want to get paid while selling a product based on Qt? Give something to Qt.

[michaelsbradley]

It’s LGPL mostly, with some non-core libraries that are GPL or use other licenses:

https://doc.qt.io/qt-6/licensing.html

Over the years it has been noted by many that Qt’s wording and warnings about the LGPL amount to spreading FUD or outright misinformation in what seems like an attempt to scare managers and C-suite folks into buying commercial licenses “just in case”.

[joezydeco]

If you get confused by it then that's all that needs to be said. The rest has been discussed over and over. I've dropped Qt for other front-end tech and I'm happier now.

[HeyLaughingBoy]

Replying to this post because the thread's getting too deep.

What was painful about switching to web tech for UI? I've proposed it at work a few times for exactly the same reasons: get away from Qt and ease of finding developers. Since our GUIs all run on Linux (we usually do the realtime stuff on an external ARM processor) it seemed like an easy transition, but I've been shot down every time.

Would be nice to hear what the downsides are.

[CoastalCoder]

I'm curious what you settled on and why. Care to elaborate?

[ogoffart]

Not OP, but some users migrated from Qt to Slint and are happy with it. [https://slint.dev] (I'm one of the Slint developers.)

[joezydeco]

I'm rooting for you guys. Keep going!

[joezydeco]

I work on equipment that can't open itself under LGPL3 rules. So I had to stop Qt use at 5.15, which went under maintenance support over 3 years ago.

I've switched to vanilla web technologies. Node, React, etc. It's painful and it sucks but hardware keeps getting faster and cheaper. I can find contractors easily and I don't need an increasingly expensive subscription^H^H^H^Hcontract with Qt to keep my developer seat hot. They tried multiple times to get me to abaondon my Qt5 license to switch to their new revenue model. I told them to fuck off.

[linhns]

Because it’s unclear and incomplete. Always prone to some KDE whims.

[Macha]

KDE is an independent project from Qt and the only say they have is they have the right to release Qt under a BSD license if Qt Group removes the GPL option ( https://kde.org/community/whatiskde/kdefreeqtfoundation/ )