In general we accept every widely acknowledged license which allows to share, modify, share the modified work, make commercial use or any combination of these. Here you see a list of licenses we accept as well as a list of licenses we don't accept. If you can't find a license in these lists or you are insecure about something, don't hesitate to ask us about it on our Discord.

Licenses are accept:

Note: re. = recommendation

[1]: Open Definition (= OD) concentrates itself only on data and content. So OD doesn't recommend nor reject licenses which were not meant for content/data in the first place.

license name our re. FSF re. OD re. Fedora re. Debian re. public domain alike perm- issive copy- left
CCO 1.0 or any later version
CC BY 3.0 or any later version
CC BY-SA 3.0 or any later version
ZLIB [1]
MIT [1]
GPLv2 or any later version [1]

Why we don't recommend Public Domain

The problem with Public Domain is that the definition is different from jurisdiction to jurisdiction (from country to country), and there is no international declaration. Also in some jurisdictions it's very complicated or even impossible to make your work Public Domain before your rights expire after the ordinary time.

Instead of Public Domain we recommend to use CC0 (Creative Commons Zero). CC0 is basically a license which gives creators a way to waive all their copyright and related rights in their works to the fullest extent allowed by law + a Public Domain fallback if the waiving of the rights isn't possible under special circumstances.

"or any later version" phrase

While some licenses which have different versions apply such an "or any later version" phrase by default, some of the licenses requires you to mention "or any later version" explicitly. E.g. the Creative Commons >= 2.0 licenses have this phrase, so everybody is allowed to license derivations of "CC BY-SA 2.0 Generic" content under the terms of "CC BY-SA 4.0 International". Other licenses like the GNU GPL license requires you to write "GPLv2 or any later version" explicitly. For every license which has or may has more than one version in the future and which doesn't have such a phrase by default we recommend to write it down yourself. This helps to prevent content from being stuck with one ancient license forever, which could be incompatible with future law.

Licenses we don't accept:

license name share modify commerical FSF OD Fedora Debian
CC BY / CC BY-SA below v3.0 ?
CC BY-ND any version
CC BY-NC any version
CC BY-NC-SA any version
CC BY-NC-ND any version
no license at all

Licenses aiming at one special jurisdiction

We reject content which is licensed under the terms of a license which aims at one special jurisdiction (country). We consider ourselves as an international community, moreover we define freedom as the freedom for everyone, everywhere. So please don't use such licenses which could cause troubles, e.g. all Creative Commons licenses before the 4.0 versions have local derivations for a lot of countries (e.g. CC BY 3.0 DE). Starting with CC v4.0 there is only one international license to address this issue.

Common mistakes:

  • Missing version number of the license (if exists), e.g. "Creative Commons BY".
  • Missing full name of the license, e.g. "licensed under a Creative Commons license".
  • Mix between the short form and the complete name, e.g. "Creative Commons BY Attribution 4.0".
  • Providing no license at all.