David A. Wheeler's Blog

Wed, 11 Jul 2007

FLOSS License Slide - Released!

There are a large number of Free-Libre / Open Source Software (FLOSS) licenses, but only a few are widely used. Unsurprisingly, the widely-used licenses tend to be compatible — that is, it’s possible to combine software under the different licenses to produce a larger work. But many people have trouble figuring out when they can be combined, or how.

So I’ve created a little figure which I call the “FLOSS license slide” to make it easier to see if FLOSS licenses can be combined in many common cases, and if so, what the basic ramifications are. I’ve crafted it so that the figure and explanatory text all fit in a page, which can be handy.

You can look at the FLOSS license slide in one of three formats:

I had released a draft of this earlier, and got some nice feedback. I added “public domain”; there seemed to be enough questions about public domain software that it made sense to add that to the figure. Yes, I know that technically “public domain” isn’t a license, but it’s much easier to understand and explain by treating it as if it were one. Some of the earlier text was not clear enough; hopefully this one is clearer. For example, GPLv2+ and the Affero GPL 3 licenses are compatible via GPLv3, but some people had trouble understanding why. Now the text notes that they are compatible via the GPL version 3, which will hopefully make that clearer. I also added the HTML format.

I’m not a lawyer, and if you need formal legal advice you need to consult your own attorney. But for many people, this is the information you needed, in a conveniently small format, so here it is. Enjoy!

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