The latest report from Marketview and the BNZ also says that online buying of electrical and electronic goods (including computers) was particularly strong - up nearly 40% compared to September last year.
In July and August, the annual growth rate had been running at around 25-30% but September's new smartphone releases may well have had an effect.
Kiwis' spending at international websites remains buoyant (+26%), some of which is to do with the weaker NZ$. But, says Marketview's report, the data suggests volumes are rising nonetheless.
Growth in online spending at local merchants mirrored that for physical goods, up 7% on September last year.