Developer Documentation

Getting Started

Create a Key

Sign up for an Ideal Postcodes account. Signing up is free and requires no payment information. Once signed in, you may create API keys via your dashboard.

Implement & Test

Once created, your key will be instantly usable on our API with test requests. You must provide the key in every API request, this is done using the api_key parameter. We provide a wide range of test methods to allow you to develop a rigorous and correct implementation. Test requests do not count towards your purchased lookups.

Go Live

When you have tested your implementation, you will be ready to take your key live and begin request live addressing data. To do this, sign in to your account and purchase lookups for the specific key. Upon successful payment, lookups will be credited to your account.

How-To Links



All API methods are either a GET, POST or OPTIONS request.

The API communicates over both HTTPS and plain HTTP using IPv4 and IPv6. Please use HTTPS whenever possible.


We use appropriate HTTP status codes where possible to indicate the request status.

All responses are returned in JSON.


Each request requires an API key for authentication. Authenticate by passing an api_key as part of the query string.

For example,

You can generate multiple API keys via your dashboard.


This API is versioned with a simple prefix in the URL. The latest version is /v1/. We maintain "backwards-compatibility" by releasing breaking changes under a new version.

Please note that we consider the following changes "backwards-compatible":

  • Adding new properties to existing API responses
  • Adding new API endpoints
  • Adding new optional request parameters to existing API endpoints
  • Changing the order of properties in existing API responses

Error Handling

A successful lookup is accompanied with a HTTP status code of 200 and a response code of 2000 (found in the body).

An error has occurred if the HTTP status code is not 200. Errors can range from the a benign 404 (resource not found) to more urgent errors (your API Key ran out of credit, failed authentication, etc).

Note that JSONP requests respond with a HTTP status code of 200 as all other responses are ignored by most browsers.


Each method has a simple testing procedure available which does not affect your account balance.


JSONP requests are supported. Simply include a callback in your request as a query parameter and your result will be returned wrapped in a function designated by your request.


Requests that affect your balance may be annotated with arbitrary metadata. This data is stored along with your lookup history and can be queried at a later date via the API or the dashboard. We call the ability to label your requests tagging.

Rate Limiting

Each IP address is rate limited at 10 requests per second for version 1 of the API. Tripping the rate limit will result in a 503 response.

If you expect to breach the limit please contact us and we can move you to an endpoint with a higher limit.

Community Key

Our documentation and demos make heavy use of our community key iddqd, which allows convenient access for trialing the API.

Although many restrictions on this key are relaxed to allow developers make test requests, this key has a limit of 15 lookups per IP address per day as well as a daily usage cap. If you hit any limit restrictions, you can continue testing the API by creating a key of your own and using our free test methods.

Please be kind with the community key. We're trusting everyone to use it responsibly so that other developers may quickly trial the API. Thank you!