ArkivDK is a free website that allows you to search over 500 Danish Archives in one search.
“Some material is digitized, so you can immediately see it here on arkiv.dk. But there is a long way to go before everything is digital, so in many cases you should contact directly to a file to view the material. …It is a good idea to send an email to the archive in advance so they can have the material ready to you when you come. …Many archives have material waiting for the final registration and therefore can not yet be seen on Arkiv.dk, so if you do not find what you are looking for, it’s also a good idea to contact a archive directly.”