# API First

Everyone **MUST** follow the **API First** principle.

The API first principle is an extension of design-first principle. Therefore, a development of an API **MUST** always start with API design without any upfront coding activities.

**API design** (e.g., description, schema) **is the master of truth, not the API implementation.**

API implementation **MUST** always be compliant to a particular API design which represents the [contract](contract.md) between API, and it's consumer.