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• GÉANT Open Source Licensing and Compliance workshop recording and slides, https://e-academy.geant.org/moodle/mod/resource/view.php?id=2869

• What is Free Software? https://www.gnu.org/philosophy/free-sw.en.html

• Guide to open source licenses, overall description, https://www.synopsys.com/blogs/software-security/open-source-licenses/
• Top open source licenses and legal risk for developers, top 20 categorised by risk, https://www.synopsys.com/blogs/software-security/top-open-source-licenses/
• Standardised SPDX licence codes and licence texts, https://spdx.org/licenses/
• University of Pittsburgh Library System – Copyright and Intellectual Property Toolkit, https://pitt.libguides.com/copyright
• WhiteSource – Open Source Licenses Explained, https://www.whitesourcesoftware.com/resources/blog/open-source-licenses-explained/
• Free Software Foundation's free software licences and Non-free Software Licenses, classified individual licences and their compatibility with GPL, https://www.gnu.org/licenses/license-list.html
• Open Source Initiative (OSI) approved licenses
  • By category, https://opensource.org/licenses/category
  • Alphabetical https://opensource.org/licenses/alphabetical

Permissive and copyleft

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licences

(Based on materials from ORCRO)

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• Choose an open-source license, https://choosealicense.com/appendix/
• Joinup Licensing Assistant – Find and compare software licenses, https://joinup.ec.europa.eu/collection/eupl/solution/joinup-licensing-assistant/jla-find-and-compare-software-licenses
• DejaCode licence finder; it can filter by one or several categories, licence text and a few key characteristics
  • All, https://enterprise.dejacode.com/licenses/
  • Permissive, https://enterprise.dejacode.com/licenses/?sort=name&category=Permissive
  • Weak copyleft, https://enterprise.dejacode.com/licenses/?sort=name&category=Copyleft+Limited
  • Strong copyleft, https://enterprise.dejacode.com/licenses/?sort=name&category=Copyleft
• Wikipedia tables and classified lists
  
  • All, https://en.wikipedia.org/wiki/Comparison_of_free_and_open-source_software_licences
  • Permissive, https://en.wikipedia.org/wiki/Category:Permissive_software_licenses
  • Copyleft, https://en.wikipedia.org/wiki/Category:Copyleft_software_licenses
• GPL compatible licenses licences are listed in the 'GPL (v3) compatibility' column of the table in https://en.wikipedia.org/wiki/Comparison_of_free_and_open-source_software_licences#Approvals

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• Dual and multi-licences help in avoiding licence compatibility issues, which makes the use of components more flexible
• Dual and multi-licences help in avoiding licence compatibility issues, which makes the use of components more flexible
• You can choose a licence compatible with the one used for your software. But you cannot dual-licence your software to match some components with one and others with another licence. Licences of all used components must be compatible with all of your licences!
• “Or later”(often as “+”) licenses licences variants just imply the applicability of later, possibly still non-existing, versions of these licences. This is sometimes implied unless you explicitly decline it.
• Some licences include automatic relicensing (MPL 2.0, EUPL 1.2, CeCILL) – EUPL comes with the full and exhaustive list…

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Licence compatibility matrices or checkers

Joinup Licensing Assistant – Compatibility Checker, https://joinup.ec.europa.eu/collection/eupl/solution/joinup-licensing-assistant/jla-compatibility-checker

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Licence Compatibility Checker software

In-licences (licences of components) are in rows, out-licences in columns:

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• Matrix of GPL licences with detailed explanations, https://www.gnu.org/licenses/gpl-faq.html#AllCompatibility

EUPL 1.2

• General explanation

  Licence Compatibility, Permissivity, Reciprocity and Interoperability, general explanation and exception list approach, https://joinup.ec.europa.eu/collection/eupl/licence-compatibility-permissivity-reciprocity-and-interoperability

• What

  Matrix of EUPL compatible open source licences, what in-licences can be out-licensed under EUPL, https://joinup.ec.europa.eu/collection/eupl/matrix-eupl-compatible-open-source-licences

• When components are under EUPL

  How to use the EUPL (What about compatibility issues?), on use of components under EUPL with other licences, https://joinup.ec.europa.eu/collection/eupl/how-use-eupl#section-18

Creative Commons licences

• Can I combine material under different Creative Commons licenses in my work? https://creativecommons.org/faq/#can-i-combine-material-under-different-creative-commons-licenses-in-my-work

Risks of permissive licences

Risk mitigation against potentially harmful legal threats or behaviours by free-software licenseslicences

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