The Reciprocal Public License (RPL) is interesting in that it is the only license both OSI-approved and not FSF-approved. It is a copyleft license similar to GPL but with a "reciprocal" clause:

Regarding deployment, under the RPL your changes, bug fixes, extensions, etc. must be made available to the open source community at large when you Deploy in any form -- either internally or to an outside party. Once you start running the software you have to start sharing the software.

RPL 1.5, preamble

Specifically, clauses 6.0 and 6.1 require that any private modifications must be provided back to the licensor and the public respectively, under the RPL.

Why is this license approved by OSI but not by the FSF? Which specific essential freedoms, if any, does RPL violate? Why doesn't RPL violate any of the Open Source Definitions?

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    "it is the only license both OSI-approved and not FSF-approved": That’s not correct. There is at least also the Sybase Open Watcom Public License.
    – unor
    Jul 1, 2015 at 16:50

1 Answer 1


The FSF says:

Reciprocal Public License (#RPL)

The Reciprocal Public License is a nonfree license because of three problems. 1. It puts limits on prices charged for an initial copy. 2. It requires notification of the original developer for publication of a modified version. 3. It requires publication of any modified version that an organization uses, even privately.

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    What about what OSI says? Jul 1, 2015 at 8:03
  • @congusbongus I don't think that you posted a public explanation why they consider it an open source license. Jul 1, 2015 at 9:24
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    That's why I'm asking Jul 1, 2015 at 9:50
  • From the Wikipedia article: "The RPL was written to conform to the requirements of the Open Source Initiative to ensure that it met the goals for an Open Source license" - so it isn't really surprising that the OSI accepted it. Jul 1, 2015 at 10:01
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    Note that what the FSF says is about version 1.3 of the license, while OSI approved version 1.5 (but I don’t know if there were any changes relevant for this discussion).
    – unor
    Jul 1, 2015 at 16:55

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