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I am looking to use a javascript libray licensed under the LGPL license v3.

From what I have read so far, I understand that

If I do not make any modifications to the library, I can use the library without any restrictions.

But if I modify the library, I need to make the modified version available to the end users and also enable them to link the library dynamically.

Since I am using javascript, my code is anyways open to the end user. Also the user can dynamically link to library through the debug console.

So my question is, do I need to do anything explicitly since javascript is already open to users ?

Also, are there any other restrictions that apply which I may have missed out ?

Note: I found other answers that describe LGPL with respect to any application. But I am looking for an answer that describes how LGPL applies to javascript specifically.

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Obligatory disclaimer: if you need legal advice, you have to ask a lawyer. Take anyone else's answers with a grain of salt. – dan1111 Jun 7 '13 at 10:09

The status of GPL in combination with web-projects is a bit murky.

The basic principles of the LGPL are

  • People that you distribute a LGPL-library to must be given the possibility to obtain the source code of the exact version of the library that you distribute.
  • People that have obtained a copy of your program must have the possibility to use your program in combination with modified versions of the LGPL-libraries that your program uses

The problem with Javascript is that, to my knowledge, it is legally unclear if using a Javascript library in a (public) website counts as distribution of that library and if it does, if that implies that users must have the possibility to exercise their freedoms on that website (which would become very impractical).

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1) Why impractical? As long as you clearly state the usage of the LGPLv3 library somewhere, with the license briefing, and provide access to the website's modified (or original) source code of that library as well as a means to load your own versions of it instead, you should be good to go. 2) I'm pretty sure using the library on your website counts as conveying (distributing) it. That is the case whenever you hand over a full program or substantial portions of one to someone. 3) IANAL. All I'm laying down here is my understanding of Stallman's philosophy. – n2liquid Mar 26 '14 at 2:51

As far as I understand LGPL you have to supply a way to receive the library (and only the library). Using technics to view the code is not enough.


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