I just looked into it and it seems that Kiwibank doesn't provide any API access (you can download exports manually thought). ANZ might be a good option then :)
There has just been a project submitted to solve this on HN – https://blog.teller.io/2017/06/12/the-api-for-your-bank-acco...
But it seems to support only a handful of UK banks – no ANZ or Kiwibank.