What the GPL Licence used by WordPress Means

As many of you surely know, WordPress is released under the GPL licence, as are many other open-source software e.g. Linux.

Although you might know that WordPress is GPL-licenced, you might not be aware of what the licence actually consists of and how it affects us as users and developers.

The most common question asked is whether the GPL licence is bad business for a theme or plugin developer. This is not the case. First of all, you can find most proprietary software shared on pirate sites anyway, so it is very dubious that using a more restrictive licence will protect your plugin/theme from getting shared illegally. Secondly, you are offering more than the actual plugin/theme code to a customer. You are offering support, amongst other things. This post about the GPL by Mark Jaquith is a real eye opener and explains the effects of the GPL very clearly in non-technical terms (check out the FAQ section).

If you are still wary of releasing your whole theme/plugin under the GPL, you could also use a split licence. Basically all the PHP code in your theme or plugin has to be GPL-licenced when working with WordPress. However this does not apply to other files such as CSS and JavaScript that your theme/plugin uses. Therefore you could use the GPL for the PHP code and another protective licence for the CSS and JS code. This essentially gives you legal protection against your plugin/theme being freely distributed. Another approach plugin developers use is for the plugin to require a licence code in order to function. Thus while the plugin can be distributed freely, you will always need the activation code in order to use it.

Otto also has another post that discusses usage of the GPL licence, while an example of split licencing can be seen in the Thesis theme.

What do you think? Do you have any questions about the GPL? Has it ever affected the way you work? Let us know in the comments below.

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