There are different requirements for EU citizens and non-EU citizens.
EU: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain and Sweden.
EFTA: Iceland, Liechtenstein, Norway and Switzerland
Non-EU: Citizens of all other countries
The Danish government offers two possibilities to non-EU au pairs who wish to stay for a limited period of time in Denmark. They can enter the country either via the Working Holiday Programme or the Au Pair Programme.