Open Source Licenses

It looks like there's some confusion on various open source licenses. I'm not a lawyer, but here's a simplified interpretation of some of the more popular licenses.

GPL
The GPL has the highest buzzword status in the open source world, but is by no means the best choice for everyone. The spirit of the GPL is that you are free to use any GPL-licensed code in any software you write, but the software you write must also be released under the GPL.

In other words, you can't expect to use GPL code in closed-source, commercial software. Anybody can simply request a complete copy of the application source code at any time without paying you anything for your effort.

The original author, however, is free to re-license the same code under different terms. In other words, you can potentially use GPL-licensed software in a closed-source application if you obtain permission from the author to use it under a different set of terms.

The GPL is favored by the Linux community, and is the license that Linux itself is released under.

LGPL
The LGPL offers a bit more slack. You can use a framework or library licensed under the LGPL in your application and still keep the source of your application closed. If you make changes to the library, you generally must provide the source code of your changes.

BSD
The terms of the BSD license are much simpler than the GPL or LGPL. Essentially, you can use BSD-licensed code in any way you see fit. You can use it in either open- or closed-source software. The only significant limitation is that the original author retains the copyright.

The BSD license tends to be favored by the Mac OS X community, because the culture accepts the fact that developers should be allowed to give things away to the community without sacrificing their own ability to pay bills.

Mac OS X would not exist without the BSD license. It allowed Apple to use FreeBSD code (and contribute back changes) while still building a business around the result.


If I sit down to write some code that I plan to give away, I want as many people to be able to benefit from it as possible. This is exactly why I chose a BSD-style license for DataCrux.

From reading the GPL itself, it seems possible that the authors thought that releasing solid code under the GPL would somehow force closed-software software to move to open source. I don't know how practical this really is in general. Developing software is a serious commitment, and certain software would never get written if there's no hope of earning income for the effort.

Once someone has decided that they need to sell a product in order to justify the time investment, finding a bit of GPL-licensed code that they want to use isn't likely to change their mind. So they either keep searching for code with a less restrictive license, or write an equivalent themselves.

I respect the viewpoints of the people who favor the GPL and realize it has its place, but I think developers need to understand the repercussions before using it. You're potentially limiting your audience by going this route.

I realize an analysis of the APSL (used by Apple) would be useful here, but I don't have a solid enough understanding of it to offer advice, so I'll leave that to someone else. :)

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