Hello World API

Version and status
Available in Sandbox Yes
Sandbox base URL https://test-api.service.hmrc.gov.uk
Available in Production Yes
Production base URL https://api.service.hmrc.gov.uk


This is an example API that allows software developers to test that their applications can connect with the HMRC API Platform. It also acts as a hands-on tutorial for developers to get started with HMRC APIs.

It includes resources for testing access to the three different access levels:

  • Say hello world is an example of an unrestricted endpoint
  • Say hello user is an example of a user-restricted endpoint
  • Say hello application is an example of an application-restricted endpoint

Further details of the different access levels are given on the Authorisation page.

For more information about how to develop your own client applications, including example clients for this API, see Tutorials.


We use standard HTTP status codes to show whether an API request succeeded or not. They are usually in the range:

  • 200 to 299 if it succeeded, including code 202 if it was accepted by an API that needs to wait for further action
  • 400 to 499 if it failed because of a client error by your application
  • 500 to 599 if it failed because of an error on our server

Errors specific to each API are shown in the Endpoints section, under Response. See our reference guide for more on errors.




View API endpoints
Why do these endpoints look different?

The endpoints for this API now use the Open API Specification (OAS).

The API has not changed. You do not need to make any updates to your application if you already use this API.