API technical and data standards

​​These standards are for people building Application Programming Interfaces (APIs) in government who want to:

assure users that their service meets minimum standards

use agile methods to improve products and services

take an API-first approach to development

You should use these standards when designing, building and operating your APIs for use in government and public services. This will ensure that your APIs work better across different platforms and services.

Before you build an API, you must understand the needs of your users.

For an API, the user is a developer who wants to consume your API to deliver a service. The developer will have needs based on:

how easy it is to write code to consume your API

Making your API easy to understand means it’s more likely to be used, because developers may not read all of your documentation.

Starting with user needs will allow you to focus on simplifying the interface, removing any features that are not useful to users.

It’s faster and simpler to reuse an existing API than build one from scratch. You should only build a new API when necessary. 

You can check if there are existing internal, external or commercially available APIs by looking at internal API catalogues and the cross-government UK API Catalogue.

Make sure that any API you choose will have the right functionality to work for your use case. You must also check the licence it is provided under, to make sure you are able to use it in your service. For example, an open API provided under an open licence can be used with few restrictions, but commercial APIs may have usage limits.

API first is the practice of designing software starting with an API, before designing your web or mobile user interface.

Developing the API before the rest of the service means a platform or service can be built around the API. This will reduce the need to repeat work, if later on an API is required for your service.