My understanding is that the database at https://portal.issn.org/
contains the official information for all registered ISSNs and that
while it's free to access on a record-by-record basis, they charge for
API access and don't permit the redistribution of the results (and
goes to great length to talk about database rights they own).
I'm in a jurisdiction (New Zealand) which I don't believe has database
rights, so I'm thinking about the usefulness of compiling this into a
CSV, probably using the the RDF as the base.
Unless there is an alternative source for this information?
...let us be heard from red core to black sky