Fwd: Re: Closed-source interoperability with the GPL

Eion Robb eion at bigfoot.com
Fri Nov 2 19:33:03 EDT 2007

Hi everyone,

I got in touch with the FSF about whether it was legal or not to have a
Skype-API plugin for libpurple.  He's come back with what I had thought;
that it's legal to do so.

I've attached his email below.

Does this end the disputes now? :)


---------------------------- Original Message ----------------------------
Subject: Re: [gnu.org #345894] Closed-source interoperability with the GPL
From:    "Brett Smith via RT" <licensing at fsf.org>
Date:    Wed, October 31, 2007 9:04 am
To:      eion at bigfoot.com


Thanks for sending those details about the Skype API.  After reviewing
them, I think you've already got the right idea: since Skype uses standard
message-passing mechanisms on Windows and GNU/Linux systems, and its
interaction with client programs is relatively high-level (i.e., there
aren't entire data structures being passed between them), I see no reason
to believe that your client software is derived from Skype.  And if that's
the case, there's no legal obstacle to writing a Skype client with GPLed
software.  Your plugin should be GPLed, of course, since it's derived from
Pidgin, but the GPL does not prohibit this sort of arms'-length
communication with proprietary software.

I hope this provides the sort of guidance you were looking for.  If you
have other questions or concerns, please let me know.

Best regards,

Brett Smith
Licensing Compliance Engineer, Free Software Foundation

Please note that I am not an attorney.  This is not legal advice.

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