Something I've noticed over the past few weeks is how many big commercial websites use jQuery combined with lots of plugins - but don't admit it. They will rename the main library to something obscure, as well as the plugins. Quite a few will even remove the comments that contain the MIT/GPL license information. (just noticed today that odeon.co.uk have done exactly this)

Why are they doing this? are they abashed by the face that they are using a free and open source library?

  • 9
    Interesting question. Removing the copyright comments is infringing the license agreement, isn't it?
    – Pekka
    Jan 7, 2011 at 13:55
  • 2
    Why was this moved here?
    – Tom
    Jan 7, 2011 at 13:57
  • 7
    @Tim Post: I would say it's fully on-topic for programmers, not at all for stackoverflow. So correct decision there.
    – Orbling
    Jan 7, 2011 at 14:04
  • 3
    @marcgg: it's certainly not a programming question. Personally I voted to close as argumentative, but then again programmers.se pretty much exists to take in all those "subjective and argumentative" questions, at least in the minds of the other closers.
    – Wooble
    Jan 7, 2011 at 14:04
  • 3
    @Wooble - Programmers is not for argumentative questions. It is for subjective, but constructive questions. There may be occasion that you get back and forth, but if a question is just argumentative it has no more place in programmers than SO.
    – MIA
    Jan 7, 2011 at 14:25

9 Answers 9


Well, its the same for some projects i work on, but only because of the automated minfying Process that is part of every release.

  • This is probably the right explanation. Jan 7, 2011 at 15:05
  • Same here at my work. But the files are not simply minfied, they are combined into a single file. Otherwise there would be almost 20 different js files to download. Jan 7, 2011 at 21:47
  • I minify each part/plugin manually with Closure Compiler then label the sections with /* jQuery x.y */, hoverIntent x.y, etc to keep track. Jan 14, 2011 at 13:33

Under the definition of the MIT license, it is perfectly permissible. They are not distributing it, and even if they were, they would only have to include a copy of the license file (not required to be the header of each file).

  • Ah, good to know.
    – Pekka
    Jan 7, 2011 at 14:04
  • Good information, but I Don't think this answers the question. The OP asked why companies were doing this, not if they were allowed to. Jan 7, 2011 at 14:24
  • 1
    -1. By hosting jQuery (or any other code) on your server, your are distributing the code (at least as far as the law is concerned), and the MIT license does require the copyright notice to be left intact.
    – josh3736
    Jan 7, 2011 at 14:33
  • 3
    @josh3736 Could you point out a law that says this? GPL for example has a FAQ that specifically says this doesn't qualify as distributing. There is the Affero GPL licence if you want to disallow that kind of use. Jan 7, 2011 at 14:57
  • @Rene Saarsoo: The MIT license explicitly states the copyright should not be removed if you are going to "use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software".
    – mipadi
    Jan 7, 2011 at 16:06

Aside from the other answers, which are good guesses, the only other reason I could think to deliberately obfuscate which libraries you're using might be to minimize the impact if a remote exploit is discovered in the library.

If there was some big showstopper of a XSS hole discovered in jQuery, for instance, it might be of some benefit to have my use of it not be super obvious.

I agree with the other answerers who say it's probably a side-effect of deployment autominification.


This may be done for optimization. An end-user needs not to receive that comments. Even if they save 1kb of code by this, it may be good


Probably a misguided attempt at obfuscation, or another (arguably) misguided attempt to reduce bandwidth. I can't think of any practical or technical reason they would want to do this.

If you are curious, try emailing them asking why they removed the license information from the code.

  • 7
    doesn't minifying code remove comments?
    – SB01
    Jan 7, 2011 at 14:00

They may be using a local modified version, and have then renamed it to follow local standards parhaps?


We rename ours because we provide drop-in widgets for our customers and they might be also using a different version of jquery that's incompatible with ours.

$ could be any version of jQuery (or sometimes other libraries like prototype), but dmJQuery is always the one we support.

(We don't really rename it in the source, just do this...)

/* make sure we use this version of jQuery and not any others. */
window.dmJQuery = jQuery.noConflict(true);
  • That's why you don't rename the file you download from jQuery. I kinda doubt that jquery-1.4.4.min.js would have conflicting versions.
    – James
    Jan 7, 2011 at 16:44
  • yes, but if my script loads jquery-1.4.4.min.js, and their script loads jquery-1.4.1.min.js on the same page, we've got a version conflict... (besides, my script is bundled up into a single JS file for easy drop onto their servers...) Jan 7, 2011 at 16:50
  • The solution to that is literally identical to your current solution, isn't it? Oh... Unless your jQuery isn't first version loaded. That, and having everything in one convenient file is understandable. :-)
    – James
    Jan 7, 2011 at 17:09

As shown on the offical jQuery website, it's used by: Google, Dell, Digg, NBC, Netflix, Mozilla, WordPress and others.

It's a widely regarded and used library.

So I assume they change the name so that people don't know they use jQuery, as they'd view it negatively, because they are relying on someone else's code rather than having written it themselves.


Large website developers care about their users, I don't see any reason why they would go out of there way to obfuscate the technologies they use from the infinitesimal fraction of their users which are readying the source code of a page.