Many products / artifacts point to a webpage to declare their license. e.g. http://www.antlr.org/license.html.

The content of the webpage can change at any time. Does that mean that already published products also change their license?

Note: In the case of antlr the license actually did change.


  • Artifact foo:1.0 is released on 2016-01-01, the license is via reference to http://this.is.a.license. This webpage says it is GPL-2.0

  • on 2016-03-01 the webpage is change to say it is LGPL-2.1 and a new version foo:1.1 is released

  • on 2016-04-01 a build download version 1.0 to my local maven repo and I check the license

Q: Is it is correct to assume license for version 1.0 is LGPL-2.1 ?


Generally speaking, a future change to the code's license does not impact the license under which you received the code. If you validly received some code under the MIT license, and later the author stops offering the code under the MIT license (and offers under the GPL instead, or stops offering it altogether), that does not change the fact that the author granted you free use of the work under the MIT license.

If you did not receive a copy of the license text when you received a copy of the work, you still have permission to use it under that original license grant. However, you may have difficulty proving it, if the owner destroyed all evidence that they used to offer the code under a different license in the past. Determining whether you recieved the code under a particular license would be a matter of evidentiary fact-finding by the court, if legal action ensued. If the court found that the author really did offer you a particular license, then you are free to operate under those license terms, whatever they were at the time.

By linking to a license page, the author can easily say, "I am currently offering the code under whatever the license text on this page says." This makes things easy for the author, but more difficult for users who want to verify the exact terms of their license (as the current posted license terms may change to differ from their received license). If the software doesn't include one, users should save a copy of the license grant they received at the time of download, if they wish to refer to it in the future.

It may be possible for the copyright holder to proactively revoke a license grant to some user. I am not sure exactly how to do this, but I imagine the copyright holder would need to directly contact license recipients and inform them that their license grant is terminated. Whether this is a legally valid thing to do probably depends on the exact relationship between the licensor and licensee (is there payment or a contract involved?), how the licensor offered the software (did they explicitly say they reserved the right to revoke the license?), and the exact terms of the license (e.g., the GPLv3 is explicitly irrevocable). There is U.S. case law that strongly indicates that software under an open source license offered to the public at large can be (and may often be) irrevocable by default; see Are licenses irrevocable by default?

Regardless, revoking a license is very different from merely changing the license an author offers to future recipients.

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    Thanks, but I am looking at a way to determine the actual, intended license. e.g. I am looking at an old maven artifact which only an url reference as license. Can I assume that the content today is its license or do I have to use other means, e.g. ask ? – openCage Jun 27 '16 at 12:46
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    @openCage The content today is its license; there is almost certainly no guesswork in that conclusion.. It may have been offered under a different license in the past. If you are positive that you have received the artifact under a different license in the past, then you may use it under that license. If you never received the artifact except under its current license, then you only have rights to use it under its current license. – apsillers Jun 27 '16 at 13:04

Virtually all OSI-approved licenses grant you a copyright license to the software you downloaded at the time you downloaded it. So even if the copyright holder later changes the license, you can still keep using the software you previously downloaded under that same license.

Copyright holders can change their license at any time as long as they make it clear to users, which is then the new terms that anyone can then download software or products from their site. Obviously, if you get updates or new downloads, those bits of software are now provided under the new license.

Beyond that, you need to evaluate the specific license that you originally downloaded the software under to make any other statements. For many popular licenses, as long as you continue to follow the terms of the license from when you downloaded the software, the original copyright holder can't "take back" the license from you.

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  • Thanks, but I am looking at a way to determine the actual, intended license. e.g. I am looking at an old maven artifact which only an url reference as license. Can I assume that the content today is its license or do I have to use other means, e.g. ask. – openCage Jun 27 '16 at 12:46

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