GNU GENERAL PUBLIC LICENSE software as part of commercial product
I am developing a CRM system for small/medium companies, and i want to integrate a GPL software as a module to my system(with some modification on my demand). Will it be legal to license it as a commercial product ?
Thanks.
Answer
Using GPL in a commercial product is a very complex matter. In the times of GPLv2 there was a grey zone that's been very thoroughly cleaned up in GPLv3. To provide detailed information, you should let us know what module it is you're using and what version of GPL it falls under.
It all comes down to "is your code a derived work of the GPL module". To give a stupid example. If the GPL module is a bubblesort and your application uses the API of the module, it's a derived work, so everything falls under GPL. If you make webservice around the module, the webservice is GPL but anything using the webservice is not. In an even more grey area, if you have old code using another sort algorithm and you make a "wrapping" layer to change translate the API from the old sort to the new sort, then only the wrapping layer is GPL as the original application is not a derived work (it was available before you used the GPL module and not written with the GPL module in mind). Note that this is all highly debatable, but things like non-GPL binary linux kernel module exist based on this interpretation of GPLv2.
Like Neil already said: Falling under GPL doesn't mean you have to publish your code. Only when a person having a license for your software asks for it, you should provide it. A random person cannot just ask for the code unless he/she actually bought the application. Of course, only one person has to buy it and then he/she does whatever he/she wants with the code (like publish it for example).