From WordPress point of view — not much, beyond plugin’s header (and even there) it is hardly policed. From licensing point of view you obviously need to accommodate requirements of both licenses accordingly. At least — make clear that your combined work is under GPLv3 and which parts of it are based on Apache License … Read more
In the spirit of open source software, I would definitely start by contacting the original developer. If your changes are an improvement to the codebase, and do not take the functionality of the plugin in a new direction, collaboration may be welcomed. If your modifications are rejected by the original developer, there are some other … Read more
There is no way to prevent the free distribution of your theme. You could make it harder by selling a copy that is restricted to a license key and a salted hash of the domain. But even if you put the code for this in a pre-compiled script it will be possible to get around … Read more
Think about it. If I write a text file using the Linux kernel (GPL) and GNU software like Gnome or Bash (also GPL) using GNU Emacs (also GPL), is that text file GPL? No. I think that should answer your question. To clarify, on a general basis, the copyleft aspect of the GPL only applies … Read more
I did cast a close-vote, since this question is a duplicate of the indicated question. (A Theme and a Plugin are functionally interchangeable as extensions of WordPress; therefore, any licensing implications of one would apply equally to the other.) That said, I will offer some thoughts. Caveats: The official WordPress Foundation stance is that PHP … Read more
The plugin should have information in it regarding the license in use. Look in the readme file (could be called README, readme.txt, README.TXT, readme.md, or some other permutation), the plugin’s PHP files (there will be one with a block that begins with: /* Plugin Name: xyz . . . */ and that block will often … Read more
You can duel license your commercial product. Only the PHP code that interacts with WordPress is required to be GPL. If you really want an extensive GPL lesson you can peruse the Thesis GPL Saga files: WordPress, GPL, Thesis and Speeding Tickets Syn-Thesis 1 And Chris Pearson The Great Thesis Vs WordPress Debate Rages On … Read more
Short answer: Yes. Longer answer: Just because something is released as open-source/under the GPL doesn’t mean you can’t put it behind a paywall. All WP themes have to be licensed GPL if you distribute them, because they are derived from the WordPress code, which is itself GPL, but you can still charge for it. Your … Read more
The quick and dirty way would be to either delete the two lines that are ‘resposible’ for the message, or wrap them by comments / comment-them-out. In your theme folder ‘twentysixteen’ look for the theme file ‘footer.php’ Around line 50 look for the following two lines: <span class=”site-title”><a href=”https://wordpress.stackexchange.com/questions/230348/<?php echo esc_url( home_url(“https://wordpress.stackexchange.com/” ) ); ?>” … Read more
Yes. Use it. Edit it however you like. Redistribute it, modified or unmodified. Sell it. The GPL explicitly allows all of these things, provided that any such distribution is done also under GPL. While the GPL requires inline-documented author attribution and copyright/license information must remain intact, there is absolutely nothing wrong with removing public-facing “credit … Read more