License vs CLA

Eventually, I would like to distribute PanWriter in one of the app stores as well, or at least keep the door open to do so. Since the GPL and for example the Apple App Store are incompatible, there seem to be these options.

• keep the code GPLv3 but also get a Contributor License Agreement (CLA) from each contributor, using e.g. https://cla-assistant.io. Not sure what exactly the agreement would have to say... the FSF e.g. requires copyright transfer for their project. (CLAs is also what e.g. Signal-iOS and many larger organizations do.)

• switch to the Mozilla Public License (that's apparently what VLC does)

  The MPL is a simple copyleft license. The MPL's "file-level" copyleft is designed to encourage contributors to share modifications they make to your code, while still allowing them to combine your code with code under other licenses (open or proprietary) with minimal restrictions.

• switch to a BSD-style copyleft-free license, like the MIT license. This makes it even easier for someone to distribute a clone of the app in an app store, which may or may not have been altered, charge for it, etc. – all without contributing back to the community.

Interesting blog post discussing some trade-offs.

Feedback welcome!

No files, tests, or code entry points are mentioned. Start by reviewing the licensing alternatives and the app-store distribution constraint described in the issue, then establish which licensing path the project will adopt; done means a documented decision with contributor requirements clarified.