Is it ethical and legal to modify a free plugin?

Community Forums Forums General Discussion Is it ethical and legal to modify a free plugin?

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This topic contains 2 replies, has 2 voices, and was last updated by  dev 1 year, 10 months ago.

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    I ask this question to the Genesis community even though it is not about Genesis per se. But this is the “general discussion” area so maybe it is allowed. If not, perhaps someone can point me to a different forum? I respect the collective opinions of this venue more so than what I see in the WP dot org support forums. People are helpful there, but many just don’t know what they don’t know. Not the case here. So here goes.

    There is a plugin called MyBookTable They have a free version and a paid version. This plugin will display info about different books that an author or publisher sells. It’s nice.

    We have a ‘library’ of code (not a plugin) that does something similar… click “books and calendar” here to see it

    I like their plugin a bit better than our own code (that we have to manually add to the /lib directory of the theme… and make some minor coding adjustments for each client… not too hard.. but somewhat a PITA.) Their plugin has the Facebook and Linked “like buttons” and other social media stuff built in. Our mess of code does not.

    Their plugin has a “Buy at Amazon” button (as well as others but we’ll just use Amazon in this discussion.) On the free version the developers embedded their own Amazon affiliate code. They are not up-font about this, at least anywhere on their website that I can find.

    To see what I’m complaining about, go to their demo store and click the Amazon button for Writing For Dummies and you wills see “?tag=authmedi-20″ appended to the URL.

    Each time their button is clicked and goes to an author or publishers book page on Amazon (like above) the plugin developer’s affiliate code is sent and if a book is bought they get 4%. It’s a good (clever) way of monetizing a free plugin.

    I personally think they should be totally up-front with this, but they are not. Apparently the folks are OK with it. (I’m not involved in the WP community or it’s politics.)

    I would have preferred that their Amazon button included NO affiliate code and if you wanted to use your own you would have to buy the ‘pro’ version. Currently the only options are: (1) use the button and their affiliate code goes in (no way to take it out) or (2) DO NOT use the button… which kind of defeats the purpose of the plugin… to help sell books!

    Their “pro” version lets you put in your won affiliate code but includes services our clients don’t need or want. If they charged like $10.95 for this simple plugin, maybe with just an “open” Amazon and Barnes&Noble button, we could see it. But not $50.

    It is very easy for anyone with some PHP background to edit one of the plugin PHP modules and take out their affiliate code. (They didn’t “bury” it very well at all.)

    They use the GNU General Public License Version 2, June 1991. I’ve read the license text (go to the GNU page and scroll down to #2) they include with the free version of the plugin and it says you can modify the code… which I think means you can take out their affiliate number.

    But I’m not sure I’m reading this legalese correctly… so I ask here:

    Is it ethical and legal to distribute a modified version of the plugin to clients who pay us to do their website?

    We’ll continue to use our own library of “spaghetti” code (one day we need to re-do this mash-mash of PHP) but I’m curious as to what the informed community here thinks… as these issues are way beyond my pay-grade.




    I have modified many GPL plugins in the past, often for reasons like the one you mentioned. In particular, I hate plugins that insert an invisible backlink to the plugin author’s site for no good reason.

    If the plugin uses GPL/GNU, you are welcome to modify the files as you see fit. That said, any changes you make will be wiped out the next time the plugin updates, so sometimes it’s more trouble than it’s worth. I can only speak for myself, but personally I see no ethical issues in modifying a plugin if the license allows for it.

    Andrea Whitmer, Owner/Developer, Nuts and Bolts Media
    I provide development and training services for designers • Find me on Twitter and Google+



    Thanks for the answer.

    As for updating, we could take that code out as well, but that could lead to complications if a WP upgrade breaks the plugin.

    We will continue to use our own library unless the developers bring out a low-price version and strips out their code and allows for user to input one.

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