[lambda]

There are no common open source licenses which forbid commercial use, as that is against the various different guidelines for what constitutes open source or free software (the Free Software Foundation Free Software definition: https://www.gnu.org/philosophy/free-sw.html, the Debian Free Software Guidelines: https://www.debian.org/social_contract, or the Open Source Definition: http://opensource.org/osd-annotated).

Probably the closest you can get in the form of commonly recognized license that meets those criteria is the Creative Commons Attribution-NonCommercial-ShareAlike license: http://creativecommons.org/licenses/by-nc-sa/4.0/. It was designed for creative works (books, movies, music, and so on) rather than software, so it doesn't address some technicalities that come up in the software field, but it is a license which allows modification and redistribution but not commercial use.

However, you have to ask yourself, why do you want to do this? Are you planning on selling the software commercially yourself? If someone else happens to make some money by adding features to your software and releasing them back to the community for anyone to use (which they are required to do under the terms of the GPL), does that actually hurt you? Or if they don't change it and just sell it straight, why would anyone buy that over the free version?

Why did you voluntarily forfeit making any money, even donations? Would you accept donations if offered? How about accept a contract to add a particular feature? If you won't accept that, why would you want someone else not to be able to accept such an offer to add a given feature? If your users are willing to pay for development, but you don't want to accept the money, should someone else not be able to accept the money, put the work in, and release their changes under the same license?

I would recommend sticking to the GPLv3. Most of the kinds of commercial use that are actually objectionable, like adding proprietary features and selling that version at a premium, are not possible under the GPLv3.

[quadrangle]

As you say, CC licenses are not appropriate for software. The CC-NC clause is also bad for ANYTHING because non-commercial clauses are bad and incompatible. The PRIMARY effect of an NC clause is to be a Wikipedia-incompatible clause, regardless of whether there's ever any commercial use or not.

See http://freedomdefined.org/Licenses/NC

[lambda]

I agree with you, I was just trying to answer his question while at the same time trying to clarify why he felt like a non-commercial clause was necessary.