Can I get benefits of others&#39; contributions to my GPL licensed software to use these contributions in my proprietary software?
<p>I have my own code of a software, purely coded by me. I am intending to open source it, GPLv3 or Apache 2.0. Then I will add them to Github to let others get benefits of source code and contribute back whenever needed to my software.</p>

<p>At the same time, I am intending to dual-license my software to let other companies use my software without limitations and restrictions of GPLv3 or Apache 2.0 licenses terms and conditions.</p>

<p>Now, whatever contributions get added to my open-source licensed software, <strong>can I add them simultaneously to my proprietary version of the same software? is it legal? Is it ethical?</strong></p>

<p>You can only relicense contributions submitted to your project under two circumstances:</p>

<ol>
<li>The license allows you to relicense the contribution as you see fit</li>
<li>You require the contributor to assign copyright for the change to you</li>
</ol>

<p>If someone receives the software under an open source license, they generally contribute back under the same license - the contributor owns the copyright to the change they are submitting, so you have no inherent right to take it and do with it as you see fit.  </p>

<p>If you want to use the change in your own proprietary distribution, you need permission to do so.</p>

copyright software licensing open-source-software gpl