Is it illegal to copy commercial software features into an open source project?
<p>Imagine I work for a company that has a software X, no algorithm in this software is patented.</p>
<p>If I want to create an open source software Z that has similar features as software X by looking into the code of software X and recreating the logic would that be illegal?</p>
<p>Consider that software Z would be created using different technology, different programming language and would not have copy-pasted code from X.</p>

<p>Your question mixes up two different aspects of intellectual property.</p>
<p>From a copyright point of view, it is perfectly legal to reproduce the features of a one piece of software in another. The functionlity of the software is not copyright (although the detailed <a href="https://en.wikipedia.org/wiki/Look_and_feel" rel="nofollow noreferrer">look and feel</a> of the user interface might be).</p>
<p>However you ask if you, as an employee, can do this by &quot;<em>looking into the code of software X</em>&quot;. Presumably by doing this learn something of the organisation and algorithms used. Even if you avoid direct copying, you are likely to have learned trade secrets of your employer, and <a href="https://my.eng.utah.edu/%7Ecs5060/notes/tradesecrets.pdf" rel="nofollow noreferrer">publishing these</a> is at least a civil tort in the US, and in some states a crime.</p>

software open-source-software