Prepare for Your Next REST API Interview with These Essential Questions
This comprehensive guide features 30 REST API interview questions covering basic, intermediate, and advanced concepts. Whether you’re a fresher, have 1-3 years of experience, or are a seasoned developer with 3-6 years in the field, these questions will help you master RESTful web services and ace your technical interviews.
Basic REST API Interview Questions (1-10)
1. What is a REST API?
A REST API (Representational State Transfer Application Programming Interface) is an architectural style for designing networked applications. It uses standard HTTP methods to perform CRUD operations on resources identified by URIs.[2][5]
2. What are the core principles of REST?
REST follows six principles: statelessness, client-server architecture, uniform interface, cacheability, layered system, and code on demand (optional).[1][5]
3. What are the main HTTP methods used in REST APIs?
The primary HTTP methods are GET (read), POST (create), PUT (update/replace), DELETE (delete), and PATCH (partial update).[3][7]
4. What is the difference between GET and POST methods?
GET retrieves data and is idempotent and safe, while POST creates new resources and is neither safe nor idempotent.[3][7]
5. What makes REST APIs stateless?
Each request from client to server must contain all the information needed to process it. The server doesn’t store client context between requests.[7][5]
6. What is a URI in REST APIs?
URI (Uniform Resource Identifier) uniquely identifies resources on the server, such as /api/users/123.[2][7]
7. What are HTTP status codes and why are they important?
Status codes indicate the result of HTTP requests: 200 (OK), 201 (Created), 400 (Bad Request), 401 (Unauthorized), 404 (Not Found), 500 (Internal Server Error).[3][5]
8. What is the role of the Request Header in REST APIs?
Request headers contain metadata like Content-Type, Authorization, Accept, cache settings, and client information.[2][3]
9. What does Content-Type header specify?
Content-Type specifies the media type of the resource, such as application/json or application/xml.[6]
10. Name some common response headers in REST APIs.
Common headers include Content-Length, Content-Type, Cache-Control, ETag, and Date.[3][6]
Intermediate REST API Interview Questions (11-20)
11. What is the difference between PUT and PATCH?
PUT replaces the entire resource with the provided data, while PATCH applies partial modifications to the resource.[3][6]
12. What is idempotency in REST APIs?
An idempotent method produces the same result regardless of how many times it’s called. GET, PUT, DELETE are idempotent; POST is not.[3]
13. What are safe HTTP methods?
Safe methods don’t modify resources: GET, HEAD, OPTIONS. They only retrieve data.[3]
14. How do you handle versioning in REST APIs?
Common approaches include URI versioning (/v1/users), header versioning (Accept: application/vnd.api.v1+json), or query parameter versioning.[4]
15. What is HATEOAS in REST?
HATEOAS (Hypermedia as the Engine of Application State) provides links in responses to enable clients to discover available actions dynamically.[4]
16. How would you design REST endpoints for a Zoho CRM user management system?
Endpoints: GET /api/users (list users), POST /api/users (create), GET /api/users/{id} (single user), PUT /api/users/{id} (update), DELETE /api/users/{id}.[1]
17. What is payload in REST API context?
Payload is the actual data sent in the request or response body, typically in JSON format for REST APIs.[3]
18. How do you implement pagination in REST APIs?
Use query parameters: GET /api/products?page=2&limit=20 or GET /api/products?offset=20&limit=10.[5]
19. What is caching in RESTful architecture?
Caching stores responses to reduce server load and improve performance. Use headers like Cache-Control, ETag, and Last-Modified.[3][5]
20. How would you filter resources in a Paytm payment API?
Use query parameters: GET /api/payments?status=completed&date_from=2026-01-01.[5]
Advanced REST API Interview Questions (21-30)
21. What are the core components of an HTTP request?
1. Request Line (Method, URI, HTTP Version), 2. Request Headers, 3. Empty Line, 4. Request Body.[2][3]
22. What are the core components of an HTTP response?
1. Status Line (HTTP Version, Status Code, Reason), 2. Response Headers, 3. Empty Line, 4. Response Body.[3]
23. How do you secure a Salesforce REST API?
Use HTTPS/TLS, OAuth2/JWT authentication, rate limiting, input validation, and proper error handling without exposing sensitive information.[4]
24. Design a REST API for Swiggy order management with proper error handling.
POST /api/orders
{
"restaurant_id": 123,
"items": [{"id": 1, "quantity": 2}]
}
Response: 201 Created or 400 Bad Request with error details.
[1][4]
25. What is rate limiting and how to implement it?
Rate limiting restricts API requests per user/time period to prevent abuse. Implement using API keys, tokens, or IP-based limits.[4][5]
26. Explain ETag and how it works with conditional requests.
ETag provides a unique identifier for resource versions. Clients use If-Match/If-None-Match headers for optimistic concurrency control.[5]
27. How would you handle bulk operations in an Atlassian Jira REST API?
Use batch endpoints: POST /api/issues/bulk with array of issue objects, returning 207 Multi-Status response.[4]
28. What is the difference between 401 Unauthorized and 403 Forbidden?
401 means authentication failed (missing/wrong credentials). 403 means authenticated but lacks permission for the resource.[5]
29. Design REST endpoints for Adobe Document API with search functionality.
GET /api/documents?search=invoice&type=pdf&owner_id=456
GET /api/documents/{id}/versions
POST /api/documents/{id}/share
[1][5]
30. How do you handle concurrent updates in a Flipkart inventory REST API?
Use optimistic locking with ETag/If-Match headers or pessimistic locking with database transactions. Return 409 Conflict on version mismatch.[3][4]
Bonus Tips for REST API Interviews
- Always mention appropriate HTTP status codes for scenarios
- Use nouns for resources (users, orders) not verbs
- Follow consistent naming conventions across endpoints
- Implement proper validation and error responses
- Understand authentication flows (OAuth2, JWT, Basic Auth)
Master these 30 REST API interview questions to confidently tackle interviews at product companies, SaaS platforms, and startups. Practice implementing these concepts with real API projects!
