API Design for the Frontend: Type-Safe Clients and Shapes

The way you design API usage on the frontend—request/response shapes, loading and error handling, and type safety—directly affects how much code you write and how many bugs you catch early. This post covers how to design consistent shapes, type-safe clients, and loading/error state so the frontend stays predictable and maintainable.

One consistent shape for async state

For any async operation (fetch user, submit form, load list), use a single shape so every part of the app handles it the same way.