Is taking influence from an Apache licensed software copyright infringment?
<p>This question was first posted on Open Source <a href="https://opensource.stackexchange.com/questions/5465/is-this-copyright-infringment">here</a>.</p>

<p>I'll try to be more specific about what I'm doing:</p>

<p>After using <a href="https://github.com/JeremySkinner/FluentValidation" rel="nofollow noreferrer">FluentValidation</a> for a few project I wanted to take a try at developing my own object validation API. </p>

<p>First I examined the code on GitHub to understand the logic that was applied. Then I went about writing my own code, it can be found <a href="https://github.com/JMPSequeira/JPSoft.CoreValidation" rel="nofollow noreferrer">here</a>.</p>

<p>The API's do the exactly the same, they present very similar, they work very differently and architecturally speaking they are radically apart.</p>

<p>I did not copy one line of code. But I did drew inspiration from it.</p>

<p>FluentValidation is licensed under Apache 2.0 and at the recommendation of a user in my previous question I decided to license  my project under Apache 2.0 as well, adding reference to FluentValidation's designer original copyright notice.</p>

<p>Apache grants "irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form."</p>

<p>Is it license infringement? Copyright infringement?</p>

<p>The "structure, sequence, and organization" of APIs are in principle copyrightable according to the Federal Circuit Court of Appeals. See <a href="http://www.cafc.uscourts.gov/sites/default/files/opinions-orders/13-1021.Opinion.5-7-2014.1.PDF" rel="nofollow noreferrer">Oracle v Google</a>.</p>

<p>Given that the structure, sequence, and organization of an API can be protected by copyright, the analysis would proceed like this:</p>

<ul>
<li>Is structure, sequence, and organization of the API sufficiently original (a product of a modicum of creativity). If yes, then the API is protected by copyright.</li>
<li>If the API is protected by copyright, then the court would apply the <a href="https://en.wikipedia.org/wiki/Abstraction-Filtration-Comparison_test" rel="nofollow noreferrer">abstraction-filtration-comparison test</a> to check for substantial similarity between your API and the original API.</li>
</ul>

<p>It is possible that there are defenses to infringement or other issues that could preclude copyrightability:</p>

<ul>
<li>fair use</li>
<li>merger</li>
<li>scenes a faire</li>
</ul>

<p>As long as your software is substantially different in design (which it is) then you aren't violating copyright afaik.</p>

copyright licensing open-source-software