yes, you can include Expat (MIT) licensed libraries in your GPL plugin. WordPress plugin guidelines states, Although any GPL-compatible license is acceptable, using the same license as WordPress — “GPLv2 or later” — is strongly recommended. All code, data, and images — anything stored in the plugin directory hosted on WordPress.org — must comply with … Read more
If you’re following the rules (you never want to start out by breaking them), then any WordPress plug-in you write and submit to the repository must be licensed as GPLv2. There was a huge storm of discussion over this last year because the example readme file mistakenly said “GPL, version 2 or any later version” … Read more
Everything on the Codex is GPL (or can be considered as GPL-compatible). Insofar as any part of the Theme Unit Test data are copyrightable, unless stated otherwise you may assume that the WordPress Foundation holds the copyright, and that the work is released under the GPL. Feel free to use it however you see fit!
There are two ways of going about licensing WordPress theme, You can License under GNU GPL or you can make your own license. Most of the big brand WordPress Theme Creators like WPMU Dev license under GNU GPL and then make you pay for the download. You could also do it where the download is … Read more
No, it is not a violation of the GPL to remove any files (including the license file) before uploading. The GPL does not place any restriction on use or modification of a work, but rather only on redistribution of the work or distribution of a modified/derivative work. In fact, the license states this scope explicitly: … Read more
There is no requirement to retain the “Powered by WordPress” note in the footer or the WordPress reference in the <meta> tags in your header. There is nothing in the WordPress license (GPL) that requires these remain intact. To take things a bit further … the “Powered by WordPress” tag in the footer is added … Read more
If a plugin is GPL, you have the right to modify, tweak, rebuild, and otherwise hack the plugin at your leisure. You also, under the GPL, have the right to redistribute your modified version and, ultimately, the unmodified version as well. The Gravity Forms license key is for support and updates. If you don’t have … Read more
Since WordPress is licensed as GPLv2, you can license any addition (i.e. theme) with a license that’s compatible with version 2 of the GPL. Now here’s the unfortunate part … version 1 of the aGPL is not compatible with any version of the GPL. Version 3, however, is compatible with GPLv3 … but not GPLv2. … Read more
Does this licensing scheme (for file groups) violates the WordPress license? No, only the PHP code needs to be GPL’d. A popular example is Thesis: http://mashable.com/2010/07/22/thesis-relents/ http://markjaquith.wordpress.com/2010/07/17/why-wordpress-themes-are-derivative-of-wordpress/ Do I have to publish the PHP code of the theme so it is available to everyone? You don’t have to publish it if your intention is to … Read more
Yes WordPress is licensed using the GPL v2 license so you are “free” to do whatever you want to with it (“free” as in “free speech”, not “free” as in “free beer!”.)