# API First

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

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

**API description is the master of truth, not the API implementation.**

API implementation **MUST** always be compliant to respective API description which represent the [contract](./contract.md) between API and it's consumer.