API Design Best Practices

As a Postman Student Leader, I've mentored dozens of developers on API design. Here are the principles that consistently lead to better APIs.

Core Principles

1. Use Meaningful Resource Names

    GET /api/v1/users/123/orders
    GET /api/v1/getUserOrders?userId=123

2. Implement Proper HTTP Methods

• GET: Retrieve data
• POST: Create resources
• PUT: Update entire resource
• PATCH: Partial update
• DELETE: Remove resource

3. Version Your API

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

Response Structure

Always return consistent response formats:

{
  "status": "success",
  "data": {
    "user": {
      "id": 123,
      "name": "John Doe"
    }
  },
  "meta": {
    "timestamp": "2025-01-05T10:30:00Z"
  }
}

Error Handling

Provide clear, actionable error messages:

{
  "status": "error",
  "error": {
    "code": "INVALID_EMAIL",
    "message": "Email format is invalid",
    "field": "email"
  }
}

Authentication & Security

• Use OAuth 2.0 or JWT for authentication
• Always use HTTPS
• Implement rate limiting
• Validate all inputs

Documentation

Good documentation is crucial:

• Use OpenAPI/Swagger specifications
• Provide code examples
• Include error scenarios
• Keep it updated

Testing with Postman

Create comprehensive test collections:

pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});

pm.test("Response has user data", function () {
    pm.expect(pm.response.json()).to.have.property('data');
});

Conclusion

Great API design is about making developers' lives easier. Focus on consistency, clarity, and comprehensive documentation.

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Want to learn more about API design? Check out my Postman workshops!