Contract First Development
Contract First Development is a software design approach where the API contract (e.g., OpenAPI/Swagger specification, GraphQL schema, or WSDL) is defined upfront before any implementation code is written. It emphasizes creating a clear, machine-readable interface definition that serves as the single source of truth for both client and server development. This methodology is commonly used in microservices, distributed systems, and API-driven architectures to ensure consistency and reduce integration issues.
Developers should use Contract First Development when building APIs for microservices, client-server applications, or any system where multiple teams need to work independently on different components. It prevents breaking changes, enables parallel development, and improves documentation quality by forcing explicit design decisions early. This approach is particularly valuable in regulated industries or large organizations where API stability and clear specifications are critical.