api-and-interface-design

Contract-first API design defines interface contracts before implementation to align teams and ensure clear boundaries. You need it to establish a stable source of truth for REST, GraphQL, and frontend-backend communication, preventing misuse across modules.

To design stable public interfaces, define the interface before implementation and document the contract as the primary source of truth. Enforce consistent error semantics, boundary validation, and additive extension to manage evolving public surfaces.

Standardize error handling by applying consistent error semantics across REST and GraphQL surfaces. Enforce boundary validation at API edges and external data ingestion points to ensure data contracts are maintained across internal module boundaries.

Yes, this API interface design approach applies across REST, GraphQL, module boundaries, and frontend-backend interfaces. It guides interface design tasks by enforcing contract-first design and consistent validation to manage evolving public surfaces effectively.

The best way to manage evolving API surfaces is through additive extension. By defining stable contracts upfront and enforcing boundary validation, you can add new fields and endpoints without breaking existing inter-service communication consumers.

Contract-first API design may not suit highly experimental or rapidly prototyped services where interface boundaries are still undefined. It requires defining stable interfaces before implementation, which can slow down initial exploration in early-stage inter-service communication.