Orthanc Licensing: Is plugin source code required to be disclosed?

Hi guys,

here’s a licensing question. Orthanc is licensed under GPLv3, which means all code linked with GPL 3.0 source code must be disclosed under a GPL 3.0 compatible license [1].
So, the question whether a plugin is automatically forced to be distributed under GPLv3 depends on how the Orthanc core calls the plugin [2].

What’s the maintainer’s stance on this topic? Are plugins legally required to be disclosed? If so, what is the disclosure procedure?


[1] https://tldrlegal.com/license/gnu-general-public-license-v3-(gpl-3)
[2] https://www.gnu.org/licenses/gpl-faq.en.html#GPLPlugins


Yes, a plugin is forced to be distributed under GPLv3 or AGPLv3, as it is a derivative work of Orthanc (it cannot run without its hosting Orthanc server).

From the GPL FAQ: “If the main program dynamically links plug-ins, and they make function calls to each other and share data structures, we believe they form a single combined program, which must be treated as an extension of both the main program and the plug-ins.” [1]

You are free to choose the way of disclosing the code of such a contributed plugin. We nonetheless invite you to index it at the following locations:



[1] https://www.gnu.org/licenses/gpl-faq.en.html#GPLPlugins

Thanks Sébastien, that’s what I thought. Thanks for clarifying!

Have a nice day!