We found this native spider under a rotting log. They come out at night to hunt.

It's a Uliodon species from the family Zoropsidae. According to Te Papa, the national museum of New Zealand, there are probably about 20 species of Uliodon in New Zealand, most not yet described (let alone understood ecologically). The Te Papa website also mentions that there is one account of someone getting a painful bite from these spiders, but that they prefer to run away (or, in the case of our spider, just sit there and wait until we go away).