api-design-principles

# API Design Principles

Master REST and GraphQL API design principles to build intuitive, scalable, and maintainable APIs that delight developers and stand the test of time.

## When to Use This Skill

- Designing new REST or GraphQL APIs
- Refactoring existing APIs for better usability
- Establishing API design standards for your team
- Reviewing API specifications before implementation
- Migrating between API paradigms (REST to GraphQL, etc.)
- Creating developer-friendly API documentation
- Optimizing APIs for specific use cases (mobile, third-party integrations)

## Core Concepts

### 1. RESTful Design Principles

**Resource-Oriented Architecture**

- Resources are nouns (users, orders, products), not verbs
- Use HTTP methods for actions (GET, POST, PUT, PATCH, DELETE)
- URLs represent resource hierarchies
- Consistent naming conventions

**HTTP Methods Semantics:**

- `GET`: Retrieve resources (idempotent, safe)
- `POST`: Create new resources
- `PUT`: Replace entire resource (idempotent)
- `PATCH`: Partial resource updates
- `DELETE`: Remove resources (idempotent)

### 2. GraphQL Design Principles

**Schema-First Development**

- Types define your domain model
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