Address Services

API

Australian Postcode Lookup API

Q: What format does the postcode need to be in?

A standard 4-digit Australian postcode as a string (e.g., "2000", "3000", "0800"). Leading zeros are preserved.

Q: What if a postcode doesn't exist?

The API returns an empty array. No error — just no results. Your application can handle this however makes sense for your use case.

Q: Does it include PO Box postcodes?

The endpoint returns localities from the dataset, which focuses on physical delivery addresses. PO Box-only postcodes may return fewer results.

Q: How many suburbs can a single postcode have?

It varies. Metro postcodes typically cover 1–3 suburbs. Regional postcodes can cover a dozen or more localities.

Enter a 4-digit postcode, get back every suburb and locality it covers — Australia and New Zealand. Instant, structured, and always up to date.

2,600+

Postcodes

17K+

Localities

<1ms

Response Time

All States

Coverage

A single postcode can cover one suburb or a dozen. If you're building shipping calculators, service area selectors, or zone-based pricing, you need to know exactly which localities sit behind each postcode.

The postcode lookup endpoint takes a 4-digit postcode and returns every suburb it covers — with state or region, locality ID, and full details. It covers both Australia and New Zealand; pass country=nz for NZ postcodes. Results come from the dataset, so they're official and up to date.

Responses are cached and typically return in under a millisecond. No external API calls, no rate-limit worries from third-party services — just a fast, reliable lookup against local data.

This is one of those endpoints that seems simple until you realise how often postcode-to-suburb mappings trip people up. Take postcode 2000 — most people think "Sydney CBD", but it actually covers Sydney, The Rocks, Millers Point, Dawes Point, Haymarket, and a handful of other localities. If you're setting delivery zones by postcode, you need that full list. If you're validating form input, you need to know whether the suburb a customer typed actually belongs to the postcode they entered.

The data comes straight from the Geoscape, updated quarterly. Postcode boundaries do change — Australia Post reassigns them occasionally, and new subdivisions get new mappings. We pick up those changes with each release so you're not running against stale data from 2019. If you need the reverse — searching for a suburb by name and getting its postcode — the suburb autocomplete endpoint does exactly that.

What you get

Endpoint capabilities and technical details.

Complete suburb list

Returns every principal locality for a given postcode. No missing suburbs, no stale data — the full list from the dataset.

Sub-millisecond response

Direct database lookup with caching. No external service calls, no variable latency — consistently fast.

State and locality IDs

Every result includes the state abbreviation, full state name, and a unique locality ID for cross-referencing with other Checkify endpoints.

All states and territories

Covers every postcode in NSW, VIC, QLD, SA, WA, TAS, NT, and ACT.

Why use this endpoint

Accurate zone pricing

Map postcodes to suburbs to set shipping zones, delivery fees, or service area boundaries without maintaining your own postcode table.

Form auto-fill

When a user enters a postcode, auto-populate the suburb dropdown with valid options. Eliminates mismatches between postcode and suburb.

Always current

Postcode-to-suburb mappings change when Australia Post reassigns them. Our data is refreshed quarterly from the official release, so you're never working with stale mappings.

Built for your industry

Common use cases across industries that rely on validated Australian data.

E-commerce

Shipping calculators and delivery zone selection based on postcode-to-suburb mappings.

Telecommunications

Service availability checks — does a postcode fall within your coverage area?

Insurance

Risk zone lookups based on postcode, tied to official locality boundaries.

Food Delivery

Delivery radius checks using postcode-to-suburb resolution for coverage validation.

Data Integrity

Trusted data, transparent pricing

Postcode and locality data sourced from the dataset (Geoscape Australia, CC BY 4.0). Updated quarterly.

Source: Geoscape

Transparent Pricing

How search units work

Checkify uses a simple unit-based model. Each paid API call costs 1–3 search units depending on the endpoint. Your monthly plan includes a set number of units — use them on any endpoint, any time. No hidden fees.

This endpoint: 1 unit per call

1 unit deducted per successful API call.

Estimate your monthly usage

Developer Corner

Ready to integrate?

One REST endpoint, JSON responses, Bearer token auth. No SDK required — just HTTP. Check the full docs for parameters, response schemas, and error codes.

API Docs Try Live Demo

Request curl

curl -H "Authorization: Bearer ck_prv_..." \
  "https://checkify.com.au/api/v1/postcode?postcode=2000"

Response JSON

[
  {
    "localityId": "NSW3325",
    "city": "SYDNEY",
    "postcode": "2000",
    "state": "NSW",
    "stateFull": "New South Wales",
    "country": "AU"
  },
  {
    "localityId": "NSW3411",
    "city": "DARLING HARBOUR",
    "postcode": "2000",
    "state": "NSW",
    "stateFull": "New South Wales",
    "country": "AU"
  }
]

Frequently asked questions

What format does the postcode need to be in?

A standard 4-digit Australian postcode as a string (e.g., "2000", "3000", "0800"). Leading zeros are preserved.

What if a postcode doesn't exist?