Exactly.  Which is fine for free software, but obviously no sane person trying to sell a piece of software would release it under those terms.

I’d say it probably is a violation, but I’m not certain.

If you’re using GPL’d code, you have to GPL the whole application - web app or not. 

What you can use in a closed-source application is code that has been released using the LGPL license. 

You have to credit the author of the LGPL’d code, and make the code you used available for others using your application, but you don’t have to GPL your entire application.

I realize this page is stale, but here’s a response on the concerns about using GPL’d items on a fee-based website.

If you did not modify the specific items that were released under GPL, there is no need to make anything available.  Even if you did modify the GPL’d items, you don’t have to release any of the other code.

For example, if you modified the menu code or the contents of the dictionary, you would be required by GPL to make THOSE SPECIFIC documents available to the public.  You don’t need to open-source any other document that is part your application.

So do you have to GPL your code because you made a call to a GPL’d product?  Hell no.  That doesn’t make any sense at all.  The whole point of GPL is to provide products that you can see/modify the source code for while ensuring you contribute when you make modifications.  It isn’t there to "infect" your own work.

I suppose it gets confusing if the GPL’d code is a short snippet that needs to be pasted into your application code.  Do you have to GPL your thousand line code because you used a 50-line snippet?  I say no.

But if you wanted to be sure, I would package that snippet in a separate file as a class or a collection of functions or a package or whatever.  Then release THAT under GPL.  And use the code in this form.  That would serve both you and the community by making the code available in a form that is easier to reuse and maintain.

I think what  empraptor says is exactly true. Think about the reasoning behind the license. It’s there to protect that open source software to always remain open source software. If anyone takes open source code and modifies it, post modification it must remain open source and licensed under GPL.

However, if you use some open source libraries you don’t need to make all your code open source and GPL licensed as well. That doesn’t make any sense at all. If you take some GPL code and modify it, place that modified code into a separate library, license it as GPL and keep the rest of your software closed and commercial under whichever license you choose.

Hi folks,
Google led me onto this page when searching info about "commercial gpl".

I think to have found the specific item in GPL’s site’s FAQ section for this problem. My understanding is that it’s never a problem to sell GPL-covered code (modified or not), it’s a problem in terms of license because as said earlier, it really infects (no other word, sorry) proprietary code.
http://www.gnu.org/licenses/gpl-faq.html#GPLInProprietarySystem

The only way described to "incorporate" GPL code into yours is to get the two pieces of software "well separated". This full-of-contradiction statement is the root of the problem because it leads to personal interpretation.

Mine is that you can reach this level of integration only if you can say "my proprietary program (as source object) uses a totally externalized program for this functionality which could be totally replaceable, via options menu or externalized configuration". I’m not even talking about source code to illustrate my point.

Applying a strong decouple-pattern to your app might be a solution, but then consider GPLing the 80% work-time consuming interface (which can be a security threat depending on your level of implementation).

To conclude, let’s have in mind that free software is not always an appropriate solution. It comes from a war based on ideas with a noble goal (the know-how and fit-to-your-needs), but is at least as extremist as the opposite side. Other licenses that are less restrictive exist, but are more rare (LGPL for instance).

Yes, the GPL infects software with which it’s combined, even if you include only ten lines of GPL’d code in a million line program of your own. The readline library, for example, is licensed under the GPL instead of the LGPL for exactly this purpose.

In general, you can safely assume that the author of a GPL’d piece of code either really does intend to prevent you from exploiting it commercially or doesn’t understand the license he placed on it. (The latter is surprisingly common.)

But I should point out that if you’re the owner of a piece of code you’d like to exploit commercially, the GPL is a great way to look free but make sure you don’t have competitors. This is why MySQL A.B. could sell themselves to Sun for a billion dollars when their only product was a "free" one.

Curt Sampson (cjs@cynic.net)

looking at http://www.gnu.org/licenses/gpl-faq.html#GPLInProprietarySystem
It says "However, in many cases you can distribute the GPL-covered software alongside your proprietary system."
and
"if the two programs are combined so that they become effectively two parts of one program, then you can’t treat them as two separate programs"

So long as the GPL backgammon software works fine without your program and your program works fine without the backgammon, then it’s OK to ship them together.

I suggest you should make your decision program an .exe file which takes text file input and output. Also adapt the GPL backgammon software to read and write text files, so it can communicate with any decision making programs in the same way.
Make sure when you distribute the whole thing you include all the source code for the modified backgammon program.

That’s the entire point. The FSF wants to encourage the end of proprietary software and writing it for a living. If Windows wanted to include the GPL widget, it would have to become GPL. The GPL’s intent is to ensure proprietary software can’t live off free software. I’m not supporting it, just stating it objectively.