License opensource app for non-commercial

Question

I wish to create an app for studying Japanese Kanji. However I'm uncertain which license would best fit it. I want my app to be Opensource so that I can use the code for tutorials and other people may benefit from the example. I want to release the app for free so that I can improve the Japanese learning community, however I don't want that a person/company rips all my source code, polishes it a bit and sells it for money. When I look at the available popular Opensource licenses they all allow "Commercial Use" (http://choosealicense.com/licenses/). I don't mind people using my source code for practice or their own apps, as long as they also published it for free and Opensource. So what would be appropriate licenses?

The Attribution-NonCommercial-ShareAlike CC BY-NC-SA seems like what I want, but it's mentioned in their FAQ that they don't recommend this license for software (https://wiki.creativecommons.org/Frequently_Asked_Questions#Can_I_apply_a_Creative_Commons_license_to_software.3F).

Answer 1

I would recommend you to use a copyleft license like the GPL. While the GPL does not forbid to sell the software, it requires to license it under GPL when sold, so when someone polishes your application and sells it, they can sell it exactly once, because their customer can then also sell it or give it away for free. When each of their customers can underbid them on the market, their business model simply isn't sustainable. So the business model you are afraid of simply doesn't work for GPL software.

You don't find many widely used software licenses which forbid "commercial use", because "commercial use" is something which is very hard to define in a way that it isn't overly restrictive.

Some examples:

• A website offers the software (or a modified form of it) for download. The website has banner ads to cover their cost. Is that commercial use?
• A website without advertising offers an improved version for download, but the software is modified to show banner ads. Is that commercial use?
• I create a fork of your software and offer it for free under the same license conditions. But I ask people to send me voluntary donations when they want to support my work on the software. Is that commercial use?
• A private school wants to use a modified version in their lessons. The program is given to the students for free, but the version is heavily optimized for the schools curriculum and teaching practices. Is that commercial use?
• I use your program to learn Japanese and/or programming. Then I use the skills I learned to make lots of money. Is that commercial use?

Maybe you say "yes" to some and "no" to others of these examples. But I think it should give you an idea how hard it can be to define "commercial use".

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