What does “API First” development mean?

"API First" development refers to the practice of designing the application programming interface (API) prior to the development of the actual application or its implementation. This approach emphasizes the importance of thoroughly defining the API's structure, endpoints, and behavior from the outset, ensuring that it meets the needs of both the developers and users who will interact with it. By prioritizing the API design process, teams can align on functionality, improve communication, and facilitate easier integration with other systems or services.

This methodology leads to better planning and can result in a more cohesive development process, where the API itself serves as a contract that guides the implementation. It helps to avoid issues that may arise if the API is designed reactively, ensuring that the final implementation adheres to the initial vision and functionality proposed during the design phase.