While Libre.fm is not meant merely as a free alternative to Last.fm, we still want it to be free. As such, all the content available through Libre.fm should be freely licensed. [http://creativecommons.org/licenses/by-sa/2.0/ CC-by-sa] is a good, but it's not the only licensing option available. [http://www.gnu.org/philosophy/license-list.html#OtherLicenses The FSF License list] has a short list of licenses that are free and useful for non-software data.


CC licenses are not compatible with users' listening stats, because many countries have special database laws. The [http://wiki.openstreetmap.org/wiki/Open_Database_License Open Database License] may be a good alternative. However, users should have the option to set whether their individual listening data may be commercially used. It could work like this: When a user sets his/her listening data to non-commercial, stats are either submitted anonymously to the overall database (which should be plain OpenDBL) or not at all.


The [http://www.okfn.org/ Open Knowledge Foundation] has a [http://wiki.okfn.org/OpenDataLicensing Guide to Open Data Licensing]. OKFN also maintains a [http://www.opendefinition.org/licenses/ list of licenses conformant with its Open Knowledge Definition]. Public domain-like options for data include [http://creativecommons.org/publicdomain/zero/1.0/ CCZero] and the [http://www.opendatacommons.org/licenses/pddl/1.0/ Open Data Commons Public Domain Dedication and Licence].