I plan to publish a small android app as open source. I use 2 libraries. One is licensed under Apache License v2 the other one is under EPL1.0.

Initially I wanted to license my work under GPLv3, but I read EPL1.0 is not GPL compatible. The developer of that library wrote me I could do what I want, but I'm reluctant to do this. I asked him if he could re-license it under EPL2.0 with secondary license since this would render it compatible, but it is unsure whether he will.

My project is written in java and I use that library not through a .jar, but I have copied the source into my project in a library directory (the source in that dir is even with the latest one of the author, I removed the unneeded files and binaries but kept readme & license). In case you are wondering, I don't use the jar because to publish the APK on F-Droid app store they ask to remove jars/binaries and to ship the source code instead.


  • Does using this EPL1.0 library this way effectively prevent me from licensing my work under GPLv3 ?

  • In that case, would it actually be possible for me to use his work with my app licensed under EPL2.0 with secondary license GPLv3 ?

Thank you

  • "The developer of that library wrote me I could do what I want" that sounds to me like permission to publish the whole, combined work under GPLv3. To be sure, we'd need to know more exactly what he said.
    – MadHatter
    Mar 28 '21 at 16:30
  • Is it ok to publish here what he wrote (without giving names) ? That's in an email and I'm not sure that this can be taken in account for licensing terms...
    – usilo
    Mar 28 '21 at 16:34
  • If permission is granted to do a thing, then (generally speaking) how it is given doesn't affect its validity (though it may affect how difficult it is to prove it was granted). As for whether you can quote the email here, that's entirely up to you, and you must decide whether you think it's permissible. What we can't do, though, is comment on what permission you have been granted without seeing the exact details. Without permission to relicense the EPLv1 work in some way, I do not think you may do what you want to do.
    – MadHatter
    Mar 29 '21 at 6:38
  • @MadHatter When you say "I do not think you may do what you want to do" does it also apply to "license my work under EPL2.0 with secondary license GPLv3" ? In this cas, is then my only alternative EPL2.0 ?
    – usilo
    Mar 29 '21 at 6:57
  • I am saying that unless the original author is willing to licence the work to you either under EPLv2 plus GPLv2+/GPLv3 as secondary licence, or under GPLv3, or under some other set of GPLv3-compatible terms, then you cannot publish the app under GPLv3. That's why understanding what permissions you have already been given is key to understanding what you may do right now.
    – MadHatter
    Mar 29 '21 at 7:50

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