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Comment by distances | Hacker News Reader

Qt-as-the-company has always made it very clear that you can't switch your Qt LGPL/GPL project to a commercial one if you didn't start with the commercial Qt license from the beginning.

You're right, it does sound a bit nasty. No, I haven't read the license myself. It's been brought up multiple times on official Qt blog comments and mailing lists, though.

Edit: checked it now, and it's clearly written at https://www.qt.io/faq/, "Developing with a Commercial License":

> Q: If I have started development of a project using the open source version (LGPL), can I later purchase a commercial version of Qt and move my code under that license?

> A: This is not permitted without written consent from The Qt Company. If you have already started the development with an open-source version of Qt, please contact The Qt Company to resolve the issue.

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It's not standard and it's not pleasant to most ears, but I think over the last 20 (!) years of development the Trolltech guys have tried to make sure they could advance Qt and make a living doing it. I respect that a lot.

OSS was a completely different animal back when this thing started. And it was forward thinking to avoid the whole problem with people demanding free support and bugfixes for open-source code.

Not saying that this is wrong, just that it's no wonder if they think this to be FUD if one isn't familiar with the rule.

As for the reasoning, a customer developing their product for years in-house and switching to commercial just before releasing would definitely place Qt financing in a shaky ground when compared to traditional commercial frameworks.

At my last company we had this situation. But they are more than happy to sort this out for free if you take a license for the next 2 years.

Good to hear!

It would be nice if they had some form of migration publicly stated. For example something like this:

If your project decides to go commercial the initial license term will include a cost of conversion based on the quantity of code already written.

It would be interesting if they expressed that rate as something like:

A gz -1 compressed tarball of the affected source code will be created, the size (in bytes) multiplied by X is the maximum fee we would charge for retroactive licensing.

I choose the wording 'maximum' there as it still allows them to offer better deals under other circumstances.

I imagine they have sales guys. If you have a meaningful amount of money to spend they will talk to you. If not, don't use their LGPL code in a proprietary product.

Qt is not an end-user, boxed product. This may shock you, but B2B software doesn't always have a public, standard price list.

Shock, no; sadden and drive me to other ventures yes.

My rule of thumb for pricing is that if someplace /makes you ask/ they aren't going to sell at a price you'd find worthwhile.

And their rule of thumb is that you aren't worth the sale. Bespoke software is not a bulk commodity. They have a free product. If you're going to be a cheapskate, use it.

The notion of charging by byte, as if software were content farming, shows that you are obviously not a professional.

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