Statistics New Zealand provides many free sources of statistical data.

Census (1996 - 2018)

figureNZ - a trust which cumulates NZ statistics from any sources

Pātaka Raraunga - Data for and about Māori

Pacific Data Fale o Aotearoa - Data for and about Pacific peoples

New Zealand Covid Statistics

19th century Aotearoa New Zealand statistical publications

Statistical publications Aotearoa New Zealand 1840-2000

Statistics of the Dominion of New Zealand 1907-1920

Yearbook Collection 1893-2012

Data 1850

Stats NZ
Includes population, regional, economy, society, environment, business and labour market statistics.

NZ Stat
Datasets viewable as tables, which can be downloaded

Infoshare
Datasets including long-term series