What is API Documentation? — UK Software Development Guide

4 min readJune 2025ClickMasters Technical TeamReviewed by James Whitmore, CTO
what is api documentation

Direct Answer

API documentation describes how to use and integrate with an API — covering available endpoints, request/response formats, authentication methods, error codes, and usage examples. Good API documentation makes an API accessible to developers who didn't build it. The industry standard for REST API documentation is OpenAPI 3.0 (formerly Swagger).

Api-documentation in the UK

OpenAPI 3.0 documentation is mandatory for UK government APIs (GDS API design guide). ClickMasters delivers OpenAPI 3.0 documentation as standard on all REST API projects — including interactive Swagger UI and Postman collections. UK GDPR implication: API documentation should not include examples containing real personal data. Use synthetic data in all documentation examples.

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