# API Design Principles

Applies REST and GraphQL design principles for intuitive, maintainable APIs.

- Repository: https://github.com/wshobson/agents (42077 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-10-30
- Runs scripts: yes, review before use

## Install

Claude Code: `npx skills add wshobson/agents --skill api-design-principles -g -a claude-code -y`
Codex: `npx skills add wshobson/agents --skill api-design-principles -g -a codex -y`
Cursor: `npx skills add wshobson/agents --skill api-design-principles -g -a cursor -y`
Gemini CLI: `npx skills add wshobson/agents --skill api-design-principles -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add wshobson/agents`

## Description

Master REST and GraphQL API design principles to build intuitive, scalable, and maintainable APIs that delight developers. Use when designing new APIs, reviewing API specifications, or establishing API design standards.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# 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
- Queries for reading data
- Mutations for modifying data
- Subscriptions for real-time updates

**Query Structure:**

- Clients request exactly what they need
- Single endpoint, multiple operations
- Strongly typed schema
- Introspection built-in

### 3. API Versioning Strategies

**URL Versioning:**

```
/api/v1/users
/api/v2/users
```

**Header Versioning:**

```
Accept: application/vnd.api+json; version=1
```

**Query Parameter Versioning:**

```
/api/users?version=1
```

## Detailed patterns and worked examples

Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient.

## Best Practices

### REST APIs

The rest: https://github.com/wshobson/agents/blob/HEAD/plugins/backend-development/skills/api-design-principles/SKILL.md