API Architecture

REST API Design Best Practices

Master REST API design principles and patterns. Learn industry best practices for building scalable, maintainable, and developer-friendly APIs that stand the test of time.

What is REST?

REST (Representational State Transfer) is an architectural style for designing networked applications. It uses HTTP protocols and leverages standard HTTP methods to perform operations on resources.

Core REST Principles:

  • • Client-Server architecture
  • • Stateless communication
  • • Cacheable responses
  • • Uniform interface
  • • Layered system

Resource Naming Conventions

✓ Best Practices

  • → Use nouns, not verbs: /users not /getUsers
  • → Use plural names: /users/123 not /user/123
  • → Use lowercase: /user-profiles not /UserProfiles
  • → Use hyphens for readability: /user-accounts not /user_accounts
  • → Keep URLs short and intuitive: /users/123/orders not /api/v1/get-user-orders-by-id

Example Resource Structure

GET    /users              # List all users
POST   /users              # Create new user
GET    /users/123          # Get specific user
PUT    /users/123          # Update user (full)
PATCH  /users/123          # Update user (partial)
DELETE /users/123          # Delete user

GET    /users/123/orders   # Get user's orders
POST   /users/123/orders   # Create order for user

HTTP Methods

GET

Read Resources

Retrieve data without side effects. Safe and idempotent.

  • • Should not modify server state
  • • Can be cached
  • • Parameters in query string
POST

Create Resources

Create new resources. Not idempotent.

  • • Data in request body
  • • Returns 201 Created with Location header
  • • Multiple calls create multiple resources
PUT

Replace Resources

Full update of existing resource. Idempotent.

  • • Complete resource in body
  • • Creates if doesn't exist (upsert)
  • • Same result on multiple calls
PATCH

Partial Update

Partial modification of resource.

  • • Only changed fields in body
  • • More efficient than PUT
  • • Use JSON Patch format
DELETE

Remove Resources

Delete specified resource. Idempotent.

  • • Returns 204 No Content
  • • Multiple deletes have same effect
  • • Consider soft deletes

HTTP Status Codes

Success (2xx)

  • 200 OK - Request succeeded
  • 201 Created - Resource created
  • 204 No Content - Success, no body
  • 206 Partial Content - Partial response

Redirection (3xx)

  • 301 Moved Permanently - Permanent redirect
  • 302 Found - Temporary redirect
  • 304 Not Modified - Cached version valid

Client Errors (4xx)

  • 400 Bad Request - Invalid syntax
  • 401 Unauthorized - Auth required
  • 403 Forbidden - No permission
  • 404 Not Found - Resource missing
  • 429 Too Many Requests - Rate limited

Server Errors (5xx)

  • 500 Internal Server Error - Server crash
  • 502 Bad Gateway - Invalid upstream
  • 503 Service Unavailable - Overloaded
  • 504 Gateway Timeout - Upstream timeout

API Versioning

1. URL Path Versioning (Recommended)

https://api.example.com/v1/users
https://api.example.com/v2/users

✓ Clear, explicit, easy to route, widely adopted

2. Header Versioning

GET /users
Accept: application/vnd.example.v2+json

More RESTful but less visible

3. Query Parameter Versioning

https://api.example.com/users?version=2

Simple but mixes versioning with query params

Authentication & Security

Common Authentication Methods

  • → API Keys: Simple but limited security (use for server-to-server)
  • → OAuth 2.0: Industry standard for user authorization
  • → JWT (JSON Web Tokens): Stateless, scalable, self-contained
  • → Basic Auth: Simple but must use HTTPS (avoid for production)

Security Best Practices

  • ✓ Always use HTTPS in production
  • ✓ Implement rate limiting to prevent abuse
  • ✓ Validate and sanitize all inputs
  • ✓ Use CORS properly for browser security
  • ✓ Never expose sensitive data in URLs
  • ✓ Implement proper error handling

Pagination & Filtering

Pagination Approaches

Offset-based (Simple):

GET /users?limit=20&offset=40

Page-based (User-friendly):

GET /users?page=3&per_page=20

Cursor-based (Scalable):

GET /users?cursor=eyJpZCI6MTIzfQ&limit=20

Filtering & Sorting

# Filtering
GET /users?status=active&role=admin

# Sorting
GET /users?sort=created_at&order=desc

# Field selection
GET /users?fields=id,name,email

# Full-text search
GET /users?q=john

Error Handling

Standard Error Response Format

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid input data",
    "details": [
      {
        "field": "email",
        "message": "Email format is invalid"
      },
      {
        "field": "age",
        "message": "Must be at least 18"
      }
    ],
    "timestamp": "2025-01-15T10:30:00Z",
    "request_id": "abc123"
  }
}

Error Response Guidelines

  • • Use appropriate HTTP status codes
  • • Provide clear, actionable error messages
  • • Include error codes for programmatic handling
  • • Never expose stack traces or internal details
  • • Include request ID for debugging

API Documentation

Essential Documentation Elements

  • → Authentication requirements and examples
  • → All endpoints with HTTP methods
  • → Request/response examples for every endpoint
  • → Parameter descriptions and constraints
  • → Status codes and error responses
  • → Rate limiting information

Popular Documentation Tools

  • • OpenAPI/Swagger: Industry standard specification
  • • Postman: Interactive API documentation
  • • Redoc: Beautiful OpenAPI documentation
  • • API Blueprint: Markdown-based format

Performance Optimization

Caching Strategies

  • • Use ETags for validation
  • • Implement Cache-Control headers
  • • Support conditional requests
  • • Cache at multiple levels

Response Optimization

  • • Enable gzip compression
  • • Implement field filtering
  • • Use pagination by default
  • • Minimize payload size

Try Our API Tools

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