Whether you can enter New Zealand without a visa depends on your nationality. Many passport holders can currently enter for periods of up to 90 days visa-free (including citizens of the United States, all European Union member states, Canada, Brazil, Argentina, and Japan). UK passport holders can enter for up to six months without a visa and Australians can enter indefinitely.
However, from July 2019, the new eTA New Zealand Electronic Travel Authorization will be implemented for all of the 60 visa exempt countries. Pre-registering an NZ eTA application online will become obligatory for these citizens from October 1st, 2019.
The only exception will be citizens of Australia, who will continue to be allowed visa-exempt travel to New Zealand. However, Australian permanent residents will also be required to apply for the eTA (but not to pay the associated International Visitor Conservation and Tourism Levy.)