How do you choose an open-source license?

Question

I'm a software engineer, not a lawyer, and my university doesn't offer any courses geared toward licensing software. In fact, their law-related courses are lacking (but slowly growing in number). Where can I go to learn about open-source licenses and how to choose them?

Answer 1

There are lots described here: http://www.gnu.org/licenses/license-list.html#SoftwareLicenses

The decision of which one to use can be political, but should ultimately be determined by your plans/desires for the software. If you want to ensure it is always free then choose GPL or another "Copyleft" license. If you don't mind some commercial use, choose another one that's compatible with that.

Answer 2

If you are looking for information regarding free and open source licenses a useful comparison chart: http://en.wikipedia.org/wiki/Comparison_of_free_software_licences

Answer 3

I almost always end up usign MIT or BSD (they're equivalent), since it

1. Is the most liberal license out there. It just says you're not responsible for any kind of trouble, and optionally forces people to include a copyright notice of your original work in derivatives.
2. It allows closed source derivatives, which is something I see as a good thing: companies sometimes don't have the possibility to do their work under the GPL (they may themselves use products or components from a third party with restricted licenses).

That, and the GNU/GPL bunch are generally extremists when you encounter them in the wild.

Answer 4

Wikipedia, of course, has basically all the information you would ever need to know. But the hard part is to know where to start. I'd recommend starting off by reading about the Apache License and the GNU GPL, which are two popular sides to the same story, each offering different freedoms to the people associated with the code.

But here it is in a nutshell: Apache License lets anyone do anything with your code, including taking it and using it in a closed source product. It gives whoever is taking the code the freedom to do what they want with it.

The GNU GPL, on the other hand, allows your code only to be used in a project that is also distributed under the GPL. In this case you might write some code and prevent a proprietary company from using your work. Here, you're giving freedom to the code itself that it will always be used for "free" purposes.

Answer 5

We had a similar dilemma. At our company we decided invest lots of time on a framework, with the eventual hope of releasing it to the open source community. The business is built using open source tools (apache, php, etc.), it was time to give back. We decided on an LGPL/MPL dual license. That way, we could incorporate fixes/improvements from the community, while still protecting applications (particularly ours) running on top of it from being forced to go open source as well.

Answer 6

More pragmatic reasons can also influence your choice of license - if you want to use a GPL library, you must use GPL yourself, or if you intend your software to be part of a larger project then you need to look at their requirements.

Answer 7

You could always just use the best one of all, the WTFPL. I use this on most of my school projects since they aren't that great anyways.

Answer 8

This can create endless discussion, but there is one tenet I would hold to whenever deciding what license to use: DON'T CREATE A NEW ONE!!

No matter how persuasive your legal guy's arguments that, because no current license exactly meets your project's unique needs, you should write your own, or even just "slightly modify" an existing one, treat him like a programmer coming to you arguing that he just HAS to use a GOTO statement because nothing else in the language will work.

Other advice:

• Choose one which has major usage (see http://freshmeat.net/stats/#license)

• See David A. Wheeler's discussion of why to choose a license compatible with the GPL - http://www.dwheeler.com/essays/gpl-compatible.html.

Answer 9

I'm slightly surprised to see no mention of the Open Source Initiative as a source of information about which open source licences exist. It probably doesn't do the comparisons, so the other sites are also worth checking.

Answer 10

I've recently begun investigating the type of licensing to apply to a rather substantial piece of work. The number of choices and the content, restrictions (or not) and limitations of all the open-source licenses is bewildering. I've found a couple good links in the answers posted, but I didn't see anything pointing to the Open Source Initiative's alphabetical list of licenses, so I've included it here.