Developed by Nets together with the banks similar to the Swedes. If you're looking for public ownership of the various organs and products that Danes interact with on a daily basis: it basically doesn't exist. Just about every software product at the municipal and state level is contracted out to an enormous private megalith that gets paid vast sums of money to execute. And they're nearly all Microsoft affiliate shops, if you were also hoping for some silver lining.
I love my country but the continuing parceling out of everything to private companies has been greatly negative to many public services. See, as an example, the DOT syndicate, which has made it prohibitively expensive to commute via public transit (why in God's name is it cheaper to travel to Germany than take a train from Copenhagen to Odense?) or the bridge to Sweden we're still paying truly insane toll fees for despite having paid for its construction years ago.