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Top 100 API Design Interview Questions and Answers

Top 100 API Design Interview Questions and Answers

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1. What is API Design?

Answer: API Design refers to the process of defining the structure, endpoints, and interactions of an Application Programming Interface (API) to enable communication between different software systems. It involves designing clean, intuitive, and efficient interfaces for developers to use.


2. What are the key principles of good API design?

Answer: Good API design should follow principles like clarity, consistency, simplicity, flexibility, and robustness. It should have clear documentation, use meaningful names, and provide a consistent way of interacting with the system.


3. What is RESTful API Design?

Answer: RESTful API Design is an architectural style that uses HTTP requests to perform CRUD operations (Create, Read, Update, Delete) on resources. It is stateless, uses standard HTTP methods, and follows a client-server architecture.

# Example of a RESTful API endpoint in Python Flask
@app.route('/users/<int:user_id>', methods=['GET'])
def get_user(user_id):
    # Code to retrieve user information
    return jsonify(user_info)

4. Explain the difference between PUT and POST methods in API design.

Answer: The PUT method is used to update or replace an existing resource at a specific URL, while the POST method is used to create a new resource. PUT is idempotent, meaning multiple requests will have the same effect as one, whereas POST is not.

# Example of using PUT method in API design
@app.route('/users/<int:user_id>', methods=['PUT'])
def update_user(user_id):
    # Code to update user information
    return jsonify(updated_user_info)

5. What is versioning in API design and why is it important?

Answer: Versioning in API design involves including a version number in the API’s endpoint URL. It allows for changes to be made to the API without breaking existing client applications. This ensures backward compatibility and a smooth transition for users.

# Example of versioning in API endpoint
GET /api/v1/users

6. Explain the purpose of status codes in API responses.

Answer: Status codes in API responses indicate the result of a request. They provide information about whether the request was successful, encountered an error, or needs further action. For example, 200 OK indicates success, while 404 Not Found indicates a resource was not found.

# Example of a status code in API response
HTTP/1.1 200 OK

7. What is pagination in API design and why is it important?

Answer: Pagination in API design involves breaking up large sets of data into smaller, manageable chunks or pages. It helps reduce the load on servers and improves response times. Pagination is crucial when dealing with large datasets to ensure efficient data retrieval.

# Example of pagination in API endpoint
GET /api/v1/users?page=2&limit=10

8. How do you handle authentication in API design?

Answer: Authentication in API design can be handled using techniques like API keys, OAuth, JWT (JSON Web Tokens), or basic authentication. These methods ensure that only authorized users can access the API’s resources.

# Example of JWT authentication in API design
@app.route('/secure-data', methods=['GET'])
@jwt_required()
def secure_data():
    # Code to handle authenticated request
    return jsonify(secure_data)

9. What is rate limiting in API design and why is it important?

Answer: Rate limiting in API design involves restricting the number of API requests a client can make within a specified time period. It helps prevent abuse and ensures fair usage of resources, maintaining the API’s performance and availability.

# Example of rate limiting in API design
from flask_limiter import Limiter

limiter = Limiter(app, key_func=get_remote_address)

@app.route('/api/v1/data', methods=['GET'])
@limiter.limit("10 per minute")
def get_data():
    # Code to handle API request
    return jsonify(data)

10. How do you handle errors and exceptions in API design?

Answer: In API design, errors and exceptions should be handled gracefully. This includes providing meaningful error messages, using appropriate HTTP status codes, and ensuring that sensitive information is not exposed in error responses.

# Example of error handling in API design
@app.errorhandler(404)
def not_found_error(error):
    return jsonify({'error': 'Not Found'}), 404

11. What is the purpose of request headers in an API?

Answer: Request headers provide additional information about the client’s request to the server. They can include details like the content type, authentication tokens, and caching instructions.

# Example of a request header
GET /api/v1/users HTTP/1.1
Host: example.com
Authorization: Bearer <token>

12. Explain the role of response headers in API design.

Answer: Response headers provide additional information about the server’s response to the client. They can include details like the content type of the response, caching directives, and information about the server.

# Example of a response header
HTTP/1.1 200 OK
Content-Type: application/json

13. What is content negotiation in API design?

Answer: Content negotiation in API design involves the process of determining the appropriate content format (e.g., JSON, XML) based on the client’s preferences specified in the Accept header. This allows for flexibility in data representation.

# Example of content negotiation in a request header
GET /api/v1/users HTTP/1.1
Host: example.com
Accept: application/json

14. How do you handle versioning in query parameters?

Answer: Versioning in query parameters involves including the version number as a parameter in the API request URL. It allows clients to specify which version of the API they want to use.

# Example of versioning in query parameters
GET /api/users?version=1

15. What is HATEOAS in API design?

Answer: HATEOAS (Hypermedia as the Engine of Application State) is a principle in API design that suggests including hyperlinks in API responses to allow clients to navigate through the application. This promotes discoverability and reduces the need for prior knowledge of API endpoints.

{
    "id": 123,
    "name": "John Doe",
    "links": [
        {"rel": "self", "href": "/api/users/123"},
        {"rel": "friends", "href": "/api/users/123/friends"}
    ]
}

16. What is the purpose of query parameters in an API endpoint?

Answer: Query parameters allow clients to include additional information in the API request URL. They are used for filtering, sorting, searching, and specifying additional options for the requested resource.

# Example of query parameters in an API endpoint
GET /api/v1/users?role=admin&sort=name

17. How do you handle file uploads in API design?

Answer: File uploads in API design are typically handled using the multipart/form-data encoding type. The server can then process the uploaded file.

# Example of file upload handling in API design using Flask
@app.route('/upload', methods=['POST'])
def upload_file():
    uploaded_file = request.files['file']
    # Code to process the uploaded file
    return jsonify({'message': 'File uploaded successfully'})

18. Explain the role of caching headers in API responses.

Answer: Caching headers in API responses provide instructions to clients and intermediary caches on how to store and reuse the response. They can improve performance by reducing the need to fetch the same data repeatedly.

# Example of caching headers in an API response
HTTP/1.1 200 OK
Cache-Control: max-age=3600

19. How do you handle cross-origin resource sharing (CORS) in API design?

Answer: CORS in API design involves configuring the server to allow or restrict requests from different origins (domains). This is done using HTTP headers to specify which origins are permitted to access the resources.

# Example of CORS configuration in Flask
from flask_cors import CORS

app = Flask(__name__)
CORS(app)

20. What is idempotency in API design?

Answer: Idempotency in API design means that a request can be made multiple times without changing the state of the system beyond the initial request. It ensures that even if a request is duplicated, the result will be the same.

# Example of an idempotent request
PUT /api/v1/users/123

21. What is the purpose of an API schema or contract?

Answer: An API schema or contract defines the structure and expectations of API requests and responses. It serves as documentation for developers, outlining the required parameters, data types, and possible outcomes.

// Example of an API schema for a user resource
{
    "type": "object",
    "properties": {
        "id": { "type": "integer" },
        "name": { "type": "string" }
    }
}

22. How do you handle authentication for a public API?

Answer: For public APIs, authentication methods like API keys or OAuth tokens are commonly used. API keys are provided to developers and act as a unique identifier, while OAuth allows third-party applications to access resources on behalf of a user.

# Example of using API key for authentication
GET /api/v1/users HTTP/1.1
Host: example.com
X-API-Key: <api_key>

23. What is the purpose of a webhook in API design?

Answer: A webhook is a mechanism that allows one system to notify another system about events or updates in real-time. It enables seamless integration between different applications and is commonly used for event-driven architectures.

# Example of setting up a webhook endpoint in Flask
@app.route('/webhook', methods=['POST'])
def webhook():
    data = request.get_json()
    # Code to handle webhook data
    return jsonify({'message': 'Webhook received successfully'})

24. How do you handle versioning in the URL path?

Answer: Versioning in the URL path involves including the version number as part of the API endpoint. This approach keeps different versions of the API distinct and allows clients to choose which version to use.

# Example of versioning in the URL path
GET /api/v1/users

25. Explain the role of content type headers in API requests.

Answer: Content type headers in API requests specify the format of the data being sent to the server. This is crucial for the server to correctly interpret and process the request body.

# Example of a content type header in an API request
POST /api/v1/users HTTP/1.1
Host: example.com
Content-Type: application/json

26. What are the advantages of using hypermedia in API responses?

Answer: Using hypermedia (HATEOAS) in API responses allows clients to navigate through the application dynamically. This reduces the need for clients to have prior knowledge of API endpoints, leading to more flexible and discoverable APIs.

{
    "id": 123,
    "name": "Jane Doe",
    "links": [
        {"rel": "self", "href": "/api/users/123"},
        {"rel": "friends", "href": "/api/users/123/friends"}
    ]
}

27. How do you handle partial updates in API design?

Answer: Partial updates in API design can be achieved using the PATCH method. This allows clients to send only the fields they want to update, rather than the entire resource.

# Example of handling partial updates using PATCH
@app.route('/users/<int:user_id>', methods=['PATCH'])
def partial_update_user(user_id):
    # Code to process partial update
    return jsonify(updated_user_info)

28. Explain the purpose of response pagination in API design.

Answer: Response pagination in API design involves breaking up large sets of data into smaller pages. This helps improve performance and allows clients to request data incrementally.

# Example of response pagination in an API response
{
    "data": [/* List of items */],
    "next_page": "/api/v1/users?page=2"
}

29. What is the role of error handling middleware in API design?

Answer: Error handling middleware in API design intercepts exceptions and errors, allowing for consistent and user-friendly error responses. It ensures that errors are handled gracefully without exposing sensitive information.

# Example of error handling middleware in Flask
@app.errorhandler(Exception)
def handle_error(e):
    # Code to handle the error and return a custom error response
    return jsonify({'error': 'An unexpected error occurred'}), 500

30. How do you handle versioning through custom request headers?

Answer: Versioning through custom headers involves clients sending a custom header (e.g., X-API-Version) to specify the desired API version. The server then uses this header to determine which version to use.

# Example of versioning through custom request header
GET /api/users HTTP/1.1
Host: example.com
X-API-Version: 1

31. How do you handle rate limiting in API design?

Answer: Rate limiting in API design involves setting restrictions on the number of requests a client can make within a specified time frame. This prevents abuse of the API and ensures fair usage.

# Example of rate limiting middleware in Flask
from flask_limiter import Limiter

limiter = Limiter(app, key_func=get_remote_address)

32. What is the purpose of an API gateway?

Answer: An API gateway acts as an entry point for multiple microservices or APIs. It can handle tasks like authentication, rate limiting, request routing, and response aggregation, providing a unified interface to clients.

# Example of an API gateway using Flask
@app.route('/api/v1/users/<int:user_id>', methods=['GET'])
def get_user(user_id):
    # Code to retrieve user information from the respective microservice

33. How do you handle versioning through content negotiation?

Answer: Versioning through content negotiation involves clients specifying the desired API version in the Accept header. The server then uses this information to determine which version to use.

# Example of versioning through content negotiation
GET /api/users HTTP/1.1
Host: example.com
Accept: application/vnd.example.v2+json

34. Explain the role of response status codes in API design.

Answer: Response status codes in API design provide information about the result of a request. They indicate whether the request was successful, encountered an error, or requires further action.

# Example of a response status code
HTTP/1.1 404 Not Found

35. How do you handle versioning through URL parameters?

Answer: Versioning through URL parameters involves including the version number as part of the API request URL. This approach allows clients to choose which version to use.

# Example of versioning through URL parameters
GET /api/v1/users

36. What is the purpose of using middleware in API design?

Answer: Middleware in API design allows for processing requests and responses at various stages of handling. It can perform tasks like authentication, validation, error handling, and logging.

# Example of middleware for authentication in Flask
@app.before_request
def authenticate():
    if not is_authenticated(request):
        return jsonify({'error': 'Unauthorized'}), 401

37. How do you handle long-running processes in API design?

Answer: For long-running processes in API design, it’s advisable to implement asynchronous endpoints. This allows the client to initiate a process and receive updates on its progress.

# Example of an asynchronous endpoint using Flask and Celery
@app.route('/process/<int:process_id>', methods=['GET'])
def get_process_status(process_id):
    task = celery.AsyncResult(process_id)
    return jsonify({'status': task.status})

38. Explain the purpose of API documentation and its formats.

Answer: API documentation provides detailed information on how to use an API, including endpoints, request parameters, response formats, and examples. It can be provided in formats like OpenAPI (formerly Swagger), RAML, or even simple markdown files.

# Example of OpenAPI documentation
openapi: 3.0.0
info:
  title: Sample API
  version: 1.0.0
paths:
  /users:
    get:
      summary: Get a list of users
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/User'

39. How do you handle binary data in API design?

Answer: Binary data in API design is typically handled by base64 encoding the data and sending it in the request body. The server then decodes it to retrieve the original binary content.

# Example of handling binary data in an API request using Flask
@app.route('/upload', methods=['POST'])
def upload_file():
    binary_data = request.files['file'].read()
    # Code to process binary data
    return jsonify({'message': 'File uploaded successfully'})

40. What is the purpose of API versioning?

Answer: API versioning allows for changes and updates to an API while ensuring backward compatibility for existing clients. It allows new features to be introduced without breaking existing functionality.

# Example of an API version in a request URL
GET /api/v1/users

41. What is the role of request headers in API design?

Answer: Request headers in API design provide additional information about the client’s request. They can include details like content type, authorization tokens, or language preferences.

# Example of a request header
GET /api/v1/users HTTP/1.1
Host: example.com
Accept-Language: en-US

42. How do you handle versioning through custom media types?

Answer: Versioning through custom media types involves defining a unique media type for each API version. Clients then specify the desired version in the Accept header.

# Example of versioning through custom media types
GET /api/users HTTP/1.1
Host: example.com
Accept: application/vnd.example.v2+json

43. What are the advantages of using JSON Web Tokens (JWT) for authentication?

Answer: JWTs are stateless tokens that can securely carry information about the user. They are compact, self-contained, and can be easily validated by the server, making them a popular choice for authentication.

# Example of generating a JWT token in Python
import jwt

payload = {'user_id': 123}
token = jwt.encode(payload, 'secret_key', algorithm='HS256')

44. How do you handle versioning through request parameters?

Answer: Versioning through request parameters involves including the version number as part of the API request URL. This approach allows clients to choose which version to use.

# Example of versioning through request parameters
GET /api/users?v=1

45. Explain the purpose of caching headers in API responses.

Answer: Caching headers in API responses instruct clients and intermediaries on how to cache the response. This can improve performance by reducing the need for redundant requests.

# Example of caching headers in an API response
Cache-Control: max-age=3600, public

46. How do you handle versioning through subdomains?

Answer: Versioning through subdomains involves including the version number as a subdomain in the API URL. This approach allows clients to choose which version to use.

# Example of versioning through subdomains
GET /v1/users

47. What is the purpose of using API keys for authentication?

Answer: API keys are unique identifiers provided to developers, allowing them to authenticate with an API. They are commonly used for public APIs and provide a simple form of access control.

# Example of using an API key for authentication
GET /api/v1/users HTTP/1.1
Host: example.com
X-API-Key: <api_key>

48. How do you handle versioning through request bodies?

Answer: Versioning through request bodies involves including the version number as part of the data sent in the request body. This approach allows clients to specify the desired version.

# Example of versioning through request body
{
    "version": 1,
    "data": {/* Data */}
}

49. What are the common authentication mechanisms for APIs?

Answer: Common authentication mechanisms for APIs include API keys, OAuth, JWT, and basic authentication. The choice of mechanism depends on factors like security requirements and use case.

# Example of basic authentication header
Authorization: Basic base64(username:password)

50. How do you handle authentication for mobile or native applications?

Answer: Mobile or native applications typically use OAuth for authentication. The client application is registered with the identity provider, and it obtains an access token for API access.

# Example of obtaining an access token using OAuth
POST /token HTTP/1.1
Host: example.com
grant_type=password&username=user&password=password

51. How do you handle errors and provide meaningful error messages in API responses?

Answer: In API design, it’s important to use appropriate HTTP status codes for different error scenarios and provide detailed error messages in the response body.

# Example of providing a meaningful error response
HTTP/1.1 404 Not Found
Content-Type: application/json

{
    "error": "User not found"
}

52. What is the purpose of hypermedia in API design?

Answer: Hypermedia in API design includes links in the response that guide the client on what actions can be taken next. It allows for dynamic navigation of the API.

// Example of hypermedia in an API response
{
    "user": {
        "id": 123,
        "name": "John Doe"
    },
    "links": [
        {"rel": "self", "href": "/api/users/123"},
        {"rel": "edit", "href": "/api/users/123/edit"}
    ]
}

53. How do you handle pagination in API responses?

Answer: Pagination in API responses involves providing metadata like total, limit, and offset to indicate the total number of items and the current range of items returned.

// Example of pagination in an API response
{
    "total": 100,
    "limit": 10,
    "offset": 0,
    "data": [/* Items */]
}

54. What is the purpose of content negotiation in API design?

Answer: Content negotiation in API design allows clients to specify the desired response format (e.g., JSON or XML) using the Accept header in the request.

# Example of content negotiation in a request
GET /api/users HTTP/1.1
Host: example.com
Accept: application/json

55. How do you handle filtering and sorting in API endpoints?

Answer: Filtering and sorting in API endpoints are typically handled through query parameters. These parameters allow clients to specify criteria for retrieving data.

# Example of filtering and sorting in an API request
GET /api/users?status=active&sort=name_asc

56. Explain the concept of idempotency in API design.

Answer: An idempotent API operation is one that can be applied multiple times without changing the result beyond the initial application. This ensures that repeating a request has the same effect as making it once.

# Example of an idempotent API operation (PUT)
PUT /api/users/123

57. How do you handle authentication for server-to-server communication?

Answer: Server-to-server communication often uses methods like API keys, OAuth client credentials, or JWTs with client credentials flow for authentication.

# Example of using client credentials grant in OAuth
POST /token HTTP/1.1
Host: example.com
grant_type=client_credentials&client_id=client_id&client_secret=client_secret

58. What is the purpose of HATEOAS in API design?

Answer: HATEOAS (Hypermedia as the Engine of Application State) is a principle in API design that includes hyperlinks in responses to allow clients to navigate the API dynamically.

// Example of HATEOAS in an API response
{
    "user": {
        "id": 123,
        "name": "John Doe"
    },
    "links": [
        {"rel": "self", "href": "/api/users/123"},
        {"rel": "edit", "href": "/api/users/123/edit"}
    ]
}

59. How do you handle versioning through custom headers?

Answer: Versioning through custom headers involves including a version header in the API request to specify the desired version.

# Example of versioning through custom headers
GET /api/users HTTP/1.1
Host: example.com
X-API-Version: 1

60. What is the purpose of rate limiting in API design?

Answer: Rate limiting in API design helps prevent abuse or overuse of resources by limiting the number of requests a client can make within a specific time period.

# Example of rate limiting in an API response header
X-Rate-Limit-Limit: 1000
X-Rate-Limit-Remaining: 950

61. How do you handle partial updates in RESTful APIs?

Answer: Partial updates in RESTful APIs are typically handled using the PATCH method along with a payload containing only the fields that need to be updated.

# Example of a partial update using the PATCH method
PATCH /api/users/123
Content-Type: application/json

{
    "name": "Jane Doe"
}

62. Explain the purpose of conditional requests in API design.

Answer: Conditional requests in API design allow clients to make a request based on certain conditions, such as the resource’s last modified timestamp.

# Example of a conditional request using If-Match header
GET /api/users/123 HTTP/1.1
Host: example.com
If-Match: "etag_value"

63. How do you handle long-running operations in API design?

Answer: Long-running operations in API design are typically handled by returning a unique identifier for the operation and providing an endpoint to check its status.

// Example of handling a long-running operation
{
    "operation_id": "12345",
    "status": "processing",
    "progress": 50
}

64. What is the purpose of content compression in API responses?

Answer: Content compression in API responses reduces the size of the payload, improving performance and reducing bandwidth usage.

# Example of content compression in an API response header
Content-Encoding: gzip

65. How do you handle versioning through URL paths?

Answer: Versioning through URL paths involves including the version number as part of the API endpoint.

# Example of versioning through URL paths
GET /api/v1/users

66. What is the purpose of using stateless authentication mechanisms like JWT?

Answer: Stateless authentication mechanisms like JWT eliminate the need to store session state on the server, making them suitable for distributed systems and microservices.

# Example of verifying a JWT token in Python
import jwt

token = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...'
payload = jwt.decode(token, 'secret_key', algorithms=['HS256'])

67. How do you handle versioning through custom media types?

Answer: Versioning through custom media types involves including a unique media type for each API version.

# Example of versioning through custom media types
GET /api/users HTTP/1.1
Host: example.com
Accept: application/vnd.example.v2+json

68. What is the purpose of using ETags in API responses?

Answer: ETags in API responses provide a way to perform conditional requests, allowing clients to check if a resource has changed since their last request.

# Example of using ETags for conditional requests
GET /api/users/123 HTTP/1.1
Host: example.com
If-None-Match: "etag_value"

69. How do you handle cross-origin resource sharing (CORS) in API design?

Answer: CORS is handled by including appropriate headers in API responses to specify which origins are allowed to access the resource.

# Example of CORS headers in an API response
Access-Control-Allow-Origin: https://example.com

70. Explain the purpose of using webhooks in API design.

Answer: Webhooks in API design allow real-time notifications to be sent to external systems when certain events occur, enabling event-driven architectures.

// Example of a webhook payload
{
    "event": "user_registered",
    "data": {
        "user_id": 123,
        "name": "John Doe"
    }
}

71. How do you handle file uploads in API endpoints?

Answer: File uploads in API endpoints are typically handled using the multipart/form-data encoding type with the POST method.

# Example of handling file uploads in an API endpoint
POST /api/upload HTTP/1.1
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW

-- ----WebKitFormBoundary7MA4YWxkTrZu0gW
Content-Disposition: form-data; name="file"; filename="example.txt"
Content-Type: text/plain

... file content ...

72. What is the purpose of using caching headers in API responses?

Answer: Caching headers in API responses (e.g., Cache-Control, ETag) allow clients to cache responses, reducing the need for repeated requests to the server.

# Example of caching headers in an API response
Cache-Control: max-age=3600

73. How do you handle API versioning for non-breaking changes?

Answer: For non-breaking changes, it’s common to include the version in the request headers or as a query parameter.

# Example of versioning through request headers
GET /api/users HTTP/1.1
Host: example.com
Api-Version: 2

74. Explain the purpose of using correlation IDs in API requests.

Answer: Correlation IDs in API requests help track a specific request across multiple services, making it easier to trace logs for debugging and troubleshooting.

# Example of including a correlation ID in an API request header
X-Correlation-ID: 12345

75. How do you handle authentication for mobile app clients?

Answer: Mobile app clients often use OAuth 2.0 with authorization code flow or implicit flow for authentication, along with secure storage of tokens.

# Example of using OAuth 2.0 in a mobile app authentication flow
https://example.com/oauth/authorize?response_type=token&client_id=client_id&redirect_uri=redirect_uri&scope=openid

76. How do you handle authentication for single-page applications (SPAs)?

Answer: Single-page applications (SPAs) often use OAuth 2.0 implicit flow for authentication, where tokens are received directly in the browser.

# Example of using OAuth 2.0 implicit flow for SPA authentication
https://example.com/oauth/authorize?response_type=token&client_id=client_id&redirect_uri=redirect_uri&scope=openid

77. What is the purpose of using HATEOAS (Hypermedia as the Engine of Application State) in API design?

Answer: HATEOAS in API design provides links to related resources, allowing clients to navigate the API dynamically without prior knowledge.

// Example of HATEOAS links in an API response
{
    "user_id": 123,
    "name": "Jane Doe",
    "_links": {
        "self": { "href": "/api/users/123" },
        "friends": { "href": "/api/users/123/friends" }
    }
}

78. How do you handle pagination in API responses?

Answer: Pagination in API responses involves including metadata like total, limit, and offset to allow clients to navigate large datasets.

// Example of pagination metadata in an API response
{
    "total": 1000,
    "limit": 10,
    "offset": 20,
    "data": [ ... ]
}

79. Explain the purpose of using API gateways in microservices architecture.

Answer: API gateways in microservices architecture serve as a single entry point for external clients, providing features like authentication, rate limiting, and request routing.

# Example of API gateway routing
GET /api/users -> [UserService]
GET /api/products -> [ProductService]

80. How do you handle error responses in API design?

Answer: Error responses in API design include appropriate HTTP status codes, along with a JSON payload providing details about the error.

// Example of an error response in an API
{
    "error": "not_found",
    "message": "Resource not found"
}

81. What is the purpose of using request throttling in API design?

Answer: Request throttling in API design limits the number of requests a client can make within a specific time period, helping to prevent abuse or overuse of resources.

# Example of request throttling headers in an API response
X-Rate-Limit-Limit: 1000
X-Rate-Limit-Remaining: 950

82. How do you handle long polling or server-sent events in API design?

Answer: Long polling or server-sent events in API design involve keeping a connection open to receive real-time updates from the server.

// Example of using server-sent events in JavaScript
const eventSource = new EventSource('/api/events');

eventSource.onmessage = (event) => {
    console.log(event.data);
};

83. How do you handle versioning in APIs for breaking changes?

Answer: For breaking changes, it’s common to include the version in the URL or as a request header.

# Example of versioning through URL
GET /api/v2/users HTTP/1.1
Host: example.com

84. Explain the purpose of using content negotiation in API design.

Answer: Content negotiation in API design allows clients to specify the format of the response they prefer (e.g., JSON, XML) using headers like Accept.

# Example of content negotiation in an API request
GET /api/users HTTP/1.1
Host: example.com
Accept: application/json

85. How do you handle partial updates to a resource in API design?

Answer: Partial updates in API design are typically handled using the PATCH method with a JSON payload containing only the fields to be updated.

# Example of partial update using PATCH method
PATCH /api/users/123 HTTP/1.1
Content-Type: application/json

{
    "name": "New Name"
}

86. What is the purpose of using rate limiting in API design?

Answer: Rate limiting in API design restricts the number of requests a client can make within a specific time period, preventing overuse and ensuring fair access.

# Example of rate limiting headers in an API response
X-Rate-Limit-Limit: 1000
X-Rate-Limit-Remaining: 950

87. How do you handle complex queries or filtering in API endpoints?

Answer: Complex queries in API endpoints are often handled using query parameters or a structured query language like OData.

# Example of complex query with query parameters
GET /api/products?category=electronics&price_less_than=1000 HTTP/1.1
Host: example.com

88. Explain the purpose of using hypermedia links in API responses.

Answer: Hypermedia links in API responses provide navigation and discoverability, allowing clients to dynamically explore the API.

// Example of hypermedia links in an API response
{
    "user_id": 123,
    "name": "John Doe",
    "_links": {
        "self": { "href": "/api/users/123" },
        "friends": { "href": "/api/users/123/friends" }
    }
}

89. How do you handle versioning in APIs when using media types?

Answer: When using media types for versioning, include the version as part of the media type in the Accept header.

# Example of versioning using media types
GET /api/users HTTP/1.1
Host: example.com
Accept: application/vnd.example.v2+json

90. How do you handle versioning in APIs using custom headers?

Answer: Versioning with custom headers involves including a custom header, such as Api-Version, in the request.

# Example of versioning using custom header
GET /api/users HTTP/1.1
Host: example.com
Api-Version: 2

91. Explain the purpose of using conditional requests in API design.

Answer: Conditional requests in API design allow clients to perform actions based on specific conditions using headers like If-Match or If-None-Match.

# Example of conditional request using If-Match header
PUT /api/products/123 HTTP/1.1
If-Match: "etag123"

92. How do you handle sorting and ordering of resources in API responses?

Answer: Sorting and ordering in API responses are often handled using query parameters like sort or by specifying it in the resource URL.

# Example of sorting using query parameter
GET /api/products?sort=name_asc HTTP/1.1
Host: example.com

93. Explain the purpose of using webhooks in API design.

Answer: Webhooks in API design allow real-time communication by sending HTTP requests to specified URLs when certain events occur.

// Example of webhook payload sent to a subscriber
{
    "event": "order_completed",
    "data": { "order_id": 1234, "total": 50 }
}

94. How do you handle versioning in APIs using subdomains?

Answer: Versioning with subdomains involves including the version as part of the domain.

# Example of versioning using subdomains
GET /v2/users HTTP/1.1
Host: v2.example.com

95. Explain the purpose of using response compression in API design.

Answer: Response compression in API design reduces payload size, improving performance and reducing bandwidth usage, especially for large responses.

# Example of enabling response compression in headers
Accept-Encoding: gzip, deflate

96. How do you handle caching in API responses?

Answer: Caching in API responses involves setting appropriate headers like Cache-Control to specify caching directives.

# Example of caching headers in an API response
Cache-Control: max-age=3600, public

97. How do you handle authentication and authorization in API design?

Answer: Authentication involves verifying the identity of a user or system. Common methods include API keys, OAuth, and JWT.

# Example of API key authentication
GET /api/users HTTP/1.1
X-API-Key: abc123

Authorization determines what actions a user can perform. This is often handled using roles and permissions.

// Example of role-based authorization in a JWT
{
    "sub": "1234567890",
    "name": "John Doe",
    "role": "admin"
}

98. Explain the purpose of using request/response validation in API design.

Answer: Request validation ensures incoming data meets specific criteria. This can prevent malformed or malicious requests.

// Example of request validation for email format
{
    "email": "invalid-email" 
}

Response validation ensures that the API’s response adheres to the expected format and structure.

// Example of response validation for a user object
{
    "id": 123,
    "name": "John Doe",
    "email": "john.doe@example.com"
}

99. How do you handle error responses in API design?

Answer: Error responses should include a meaningful HTTP status code and a JSON body providing details about the error.

// Example of an error response
HTTP/1.1 404 Not Found
Content-Type: application/json

{
    "error": "Resource not found",
    "code": 404
}

100. What are some common security practices in API design?

Answer: Common security practices in API design include:

  1. Input validation: Validate and sanitize all input to prevent injection attacks.
  2. HTTPS: Use secure connections to protect data in transit.
  3. Rate limiting: Prevent abuse or overuse of the API by limiting requests.
  4. Authentication and authorization: Ensure only authorized users can access certain resources.
  5. Data encryption: Encrypt sensitive data at rest.

These are essential practices to safeguard the integrity and security of an API.