RBNZ Exchange Rate API: Official NZD Rates as JSON

Reserve Bank of New Zealand publishes official exchange rates — 18 currencies against the NZD (plus the TWI on the bank's site) — and these are the published official rates used for tax filings, audits, and compliant invoicing in New Zealand, not moving market prices. This guide shows how to pull them as JSON: via a REST endpoint or the zero-dependency rbnz-exchange-rate npm package, with history back to 2018.

What the RBNZ publishes

• 18 currencies against the NZD (plus the TWI on the bank's site).
• History back to 2018 — queryable by exact date or as a time series.
• The bank's own publication date on every response, so a rate is always citable.
• No gaps to trip over — requests for non-publication days resolve to the most recent published rates and are flagged explicitly.

Rates are the wholesale market rates observed at around 3pm New Zealand time each business day — the B1 statistical series.

Why official rates, not market rates

A live mid-market feed answers "what is NZD/USD trading at right now?" — the right tool for checkouts and dashboards. But accountants, auditors, and tax authorities ask a different question: "which rate were you required to use for this date?" That answer comes from the central bank's published rates, and it never changes after publication.

Get the latest rates (REST)

curl "https://allratestoday.com/api/v1/central-bank/rbnz/latest" \
  -H "Authorization: Bearer YOUR_API_KEY"

The response is the bank's most recent published data — every rate and the publication date. The latest rates are available on every plan, including the free tier (300 requests/month, no credit card).

The npm SDK

npm install rbnz-exchange-rate

import { getRate, getLatestRates } from 'rbnz-exchange-rate';

// One pair at the official Reserve Bank of New Zealand rate
const pair = await getRate('NZD', 'USD', { apiKey: 'art_live_...' });
console.log(pair.rate, pair.rate_date);

// The bank's full published table
const table = await getLatestRates({ apiKey: 'art_live_...' });
console.log(table.rate_date, table.rates.length);

Zero dependencies, TypeScript types included, and it runs anywhere fetch exists — Node 18+, Bun, Deno, and edge runtimes.

Historical rates for an invoice date

import { getRatesForDate, getHistory } from 'rbnz-exchange-rate';

// The official rates for an invoice date — non-publication days return
// the most recent published date, flagged via published_on_requested_date.
const day = await getRatesForDate('2026-06-30', { apiKey: 'art_live_...' });

// Time series for one pair
const series = await getHistory(
  { source: 'NZD', target: 'USD', from: '2026-01-01' },
  { apiKey: 'art_live_...' }
);

Historical dates and time series need a paid plan; the latest rates stay free.

Published vs derived pairs

If the RBNZ does not print a pair directly, the API resolves it from the bank's published rates — an inverse, or a cross rate via NZD — and flags it derived: true with the method used. Official and computed values are never silently mixed, which is exactly the distinction an auditor will ask about.

FAQ

Does Reserve Bank of New Zealand have an official exchange rate API?

Reserve Bank of New Zealand publishes its official rates on its website, but not always in a developer-friendly form. AllRatesToday serves the bank's published rates as clean JSON — 18 currencies against the NZD (plus the TWI on the bank's site), with history back to 2018 — via REST or the rbnz-exchange-rate npm package. The latest table is free.

How often do Reserve Bank of New Zealand rates update?

Once per business day. These are published reference rates, not moving market prices — the table changes when the bank publishes a new one, and every API response carries the bank's own publication date so you can cite it.

Can I get the Reserve Bank of New Zealand rate for a past date, like an invoice date?

Yes. The /central-bank/rbnz/rates-for-date endpoint returns the official rates for any date back to 2018. Non-publication days resolve to the most recent published date and are flagged, so your audit trail stays honest. Historical dates require a paid plan; latest rates are free.