According to the European Commission - December 2017 leaflet, downloadable in .pdf format from the ISA2 site (https://ec.europa.eu/isa2/sites/isa/files/docs/publications/leaflet_eup…), the EUPL is the only Free Open Source Software with equal legal value across the EU and in 23 EU languages. It reconciles the strength of the copyleft licence with interoperability needs of the modern software.
The leaflet summarises the main four reasons for using the EUPL:
- Accessible: software distributed under the EUPL remains free and available to everyone.
- EU Law Compliant: it is valid in all Member States, with precisely formulated limitations of liability or warranty, and conforms to EU law requirements.
- Multilingual: it is available in 23 EU languages.
- Compatible: it is downstream compatible with many other copyleft licences, including business-friendly OSS licenses.
What is your opinion about this? Are copyleft and compatibility a "all-purpose" option? Would you prefer a permissive licence like the BSD-3, MIT or possibly Apache? Or a so-called "strong copyleft" like the GPL or AGPL?