API Design

APIs are the contracts between services. A well-designed API is intuitive, consistent, and resilient. This lesson covers REST, GraphQL, gRPC, versioning, pagination, rate limiting, idempotency, API gateways, and documentation.

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REST Principles

REST (Representational State Transfer) is the most common API architectural style.

Core Principles

Principle	Description
Stateless	Each request contains all information needed
Resource-based	URLs represent resources, not actions
HTTP methods	Use GET, POST, PUT, PATCH, DELETE semantically
Uniform interface	Consistent URL patterns and response formats

RESTful URL Design

Good:                              Bad:
GET    /users                      GET    /getUsers
GET    /users/123                  GET    /getUserById?id=123
POST   /users                     POST   /createUser
PUT    /users/123                  POST   /updateUser
DELETE /users/123                  POST   /deleteUser?id=123
GET    /users/123/orders           GET    /getOrdersByUser?userId=123

HTTP Methods and Status Codes