API Code-first is the practice of building an API and then using annotations or metadata to generate API documentation in formats like OpenAPI, but it faces challenges due to outdated tools and the complexity of keeping metadata in sync with code changes. Traditional methods involve embedding annotations within the code, which can become outdated if not consistently maintained, and often rely on older versions of OpenAPI. Newer approaches, such as OpenAPI-aware frameworks, automatically generate OpenAPI documentation from the code, while traffic sniffing tools can create an initial OpenAPI from existing APIs by analyzing web traffic. However, these methods often require additional effort to enhance the generated documentation with detailed descriptions and examples. As a result, many developers are moving towards an API Design-first approach, where the OpenAPI document is created before any code is written, allowing it to serve as a source of truth throughout the API lifecycle. This method helps prevent issues like code and schema drift and enables better integration with server-side validation and client testing, leading to improved productivity and accuracy over time.