Well, now we know. You can't sell software using the General Public License (GPL) on the Apple App Store& because it conflicts with its Terms of Service (ToS) . The popular VLC media player, was the first major GPLed software to be pulled from Apple's App Store, it won't be the last. But, what about Google's Android Market? I asked the experts and they tell me that, in general, GPL developers can offer their wares on Android.

I asked Columbia Law School professor Eben Moglen and head of the Software Freedom Law Center (SFLC) about whether GPLv3 programs, as well software like VLC, which is under the GPLv2, would be restricted from Apple's App Store, and he replied, "Yes. The problem isn't in the license terms. The problem is that the Apple App Store ToS for people wanting to distribute through it require that each app sold (even at price zero) must be licensed for use on a single device only. Permissively-licensed FOSS can be transacted for in the App Store, because its license can be replaced by single- device-only terms. Copylefted software can't be un-freely relicensed, so it can't be transacted for there under Apple's current ToS."

Brett Smith, the Licensing Compliance Engineer for the Free Software Foundation, agreed. "Yes, that's correct. Just like GPLv2, GPLv3 prohibits distributors from placing additional restrictions on the software through other legal documents or similar means. That's in the last paragraph of section 10."

Rob Blasi, a partner in Goodwin Procter's Technology Companies and Intellectual Property Group, added, "There are several open source licenses that prohibit re-distributors from imposing any additional restrictions on the open-source items that they have taken under that license. The GPLv3 does allow re-distributors to impose certain additional terms (e.g., disclaimers of warranties), but not the kinds of restrictions that the Free Software Foundation has taken issue with in Apple's App Store Terms of Sale."

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What about Android?

If you want to sell your GPL-software on Android though, you should be in the clear. Moglen said, "So far as we know--and we have reviewed the Google Android market terms recently, so change would have to have occurred within the last few weeks--they do not place any limitation on how a market participant's application is licensed that would inhibit distributing Android applications in the market under copyleft licensing."

Smith agrees but added a caveat, "Some of the apps in Google's Android Market are DRMed (Digital Right Management), and Google's Terms of Service puts similar restriction on those apps. But unlike Apple's App Store, developers can choose whether or not their programs are DRMed, and the Android Market Terms of Service does not impose additional restriction on programs that are not DRMed."

Blasi added, "The Terms of Service for the Android Market have one important difference - they appear to let individual developers decide the scope of the license for users obtaining software through the Android Market. That kind of flexibility should avoid the problem that we're seeing here with the Apple App Store."

Or, to boil it down, Black Duck Software, the open-source business legal and management company, Peter Vescuso, Executive VP of marketing and business development said, software vendors and developers with a GPLed iPhone/iPad app don't have the option of selling through Apple's app store. Android developers have the flexibility to use GPL license terms, so they have that market as an option."

You could also as Stephen Walli, the technical director for the Outercurve Foundation, points out, dual-license your code as "MySQL AB used to license their software to the community as free software under the GPL while continuing to sell a proprietary closed edition of the software under a separate license." To dual-license a GPLed program you need the agreement of every copyright holder with a stake in the program.

That certainly won't happen in the case of VLC, but it's conceivable that other free software communities could do this with their GPLed programs. I see this approach as being a course that's more likely to be taken by new open-source communities working on new GPLed projects.

For most developers, though, if you're creating GPL software, you can sell it through the Android Market, but not through Apple's App Store. It's that simple. Now, if Apple changes their ToS, it would be a different story, but I think I'll see Adobe Flash in the Apple iPhone App Store before that happens.