REST API Design Best Practices for Developers

Good API Design Matters

A well-designed API reduces integration time, improves developer experience, and reduces support tickets. Poor API design leads to confusion, inconsistencies, and frustrated developers.

Naming Conventions

# Good — noun, plural, kebab-case
GET    /api/v1/invoices
POST   /api/v1/invoices
GET    /api/v1/invoices/123
PUT    /api/v1/invoices/123
DELETE /api/v1/invoices/123

# Bad — verb, singular, camelCase
GET /api/getInvoice
POST /api/createInvoice

Versioning

Always version your API from day one. Use URL path versioning (/api/v1/) for simplicity. Never make breaking changes without a new version.

Error Handling

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invoice amount must be positive",
    "details": [
      {"field": "amount", "issue": "Value -50 is not allowed"}
    ]
  }
}

Documentation

Use OpenAPI (Swagger) specification for API documentation. Tools like Swagger UI, Redoc, and Postman generate interactive documentation from your OpenAPI spec. Document every endpoint, parameter, response code, and error case.