How do you compare two plugins to see if one’s a fork or stolen? What’s the difference between a fork and a clone?
Sometimes people like to ‘steal’ plugins. This normally happens when someone takes a premium (purchase only behind a firewall) plugin and attempts to give it away for free on WordPress.org. They tend to violate copyright when they do that, but also it’s just not a cool thing to do and I find it distasteful.
Often we catch these since people who steal like that aren’t always very smart and we recognize code that is generally well known and popular. But more often we don’t catch it because CodeCanyon has 3400+ plugins and WordPress.org has 37k+ and that’s a lot to compare and remember. And that’s when we get an email from a plugin developer who says “So and so stole my work!”
What do we do? We ask them for a copy of their code, in a zip, and say we’ll compare. Most developers are happy to do that. We’re a trustworthy lot, otherwise we wouldn’t be on the plugin team (yes, being a good, moral, and ethical person is very important). Once I have the zip, I download the claimed-clone and compare them line by line.
Well. Not really.
My toy is DeltaWalker.
With DeltaWalker I can compare two zip files without having to open the zips and look at each line. In the below example, I’ve got Akismet 3.0 vs 3.1.1 and I can see every single change just by tossing the zips in as files to compare:
DeltaWalker is so good, it helps me compare the readmes so I can easily see that someone has just fiddled with the original and not written their own.
What I look for is code style, formatting, and naming conventions. Rarely do two separate individuals use the same code formatting (tabs vs spaces vs tabs+space etc), so seeing their additions will jump out. Similarly, the code style, their internal logic, is often wildly different. Same with naming conventions.
When you look at it, it will jump out at you that generally all anyone does is rename functions or classes. They remove credit and copyright information too, and sometimes they mess with the help docs. Rarely do they add anything of substance. If they do then it’s a legit fork and we’ll push them to restore credit and copyright information.
But since it’s generally not, we will quickly see that the plugin is a direct, no feature added, copy, and remove it.
If this happens to you, if your plugin is ‘taken’ and duplicated without any code being added, email
pluginsATwordpress.org with a copy of your original plugin (and a link to perhaps prove it’s you) and we’ll look at it. If you get an email where we tell you that your plugin is a copy, take a moment to review your code and feel free to talk with us about it. A ‘one line’ change actually MAY be acceptable as a fork, but it’s rare unless it’s adding in a massive feature, or totally changing functionality.
Above all, remember this:
Despite the fact that all plugins in our directory are licensed under the GPL or compatible licenses, we do not allow direct copies of other plugins to be re-listed under somebody else’s name. “Forking” is acceptable only when the resulting fork is of a substantial nature, or when the original plugin is no longer updated or supported.
Always try to contribute back to the original plugin’s authors if you wish to make improvements to the original plugin, instead of creating an entirely new version and thus creating incompatibilities and duplicated code in the repository.
Alternatively, write your own plugin to perform the functionality you want to have, drawing on ideas from the original. Ideas can always be copied.