REST API Design and Versioning Interview Questions

All 66 questions

1. How do you approach REST API design, and what considerations and tools guide you?

   Asked in 11 of 377 interviews · last asked Oct 16 · Concept · Mid-level

   Show answer

   I start with client needs and model resources with clear URLs, HTTP methods, and status codes. I define request and response formats in OpenAPI and review the contract before coding. I plan security, validation, errors, pagination, and compatibility. I use Swagger UI for documentation, Postman or curl for exploration, and automated tests to check behavior.

   • Keep requests stateless, and use HTTP methods according to their meaning.
   • Use HTTPS, authenticate callers, and check permissions for each resource.
   • Keep errors consistent; define pagination, filtering, and rate limits where needed.
   • Avoid breaking clients; plan retries, idempotency, and caching where appropriate.

   What the interviewer checks: The interviewer checks whether you can turn client needs into a secure, consistent API that is easy to use and maintain.

   Other ways it was asked

   • “How do you design and develop a RESTful API?”
   • “What factors do you consider when designing or consuming REST APIs?”
   • “What do you consider when designing a REST API?”

2. How do you change an API without breaking existing clients?

   Asked in 4 of 377 interviews · last asked Oct 23 · Scenario · Mid-level

   Show answer

   I keep changes backward compatible whenever possible, so existing clients can still use the API unchanged. For breaking changes, I introduce a new version and keep the old version running during migration. I test compatibility, document the changes, and give clients time to move before retiring the old version.

   • Avoid removing fields, changing types, or making optional inputs required in an existing version.
   • Additive changes are usually safer, but strict clients may reject new fields or enum values.
   • Expose versions consistently, such as through URL paths or request headers.
   • Announce retirement dates and track old-version usage before shutting it down.

   What the interviewer checks: The interviewer checks whether you can preserve existing client behavior while planning and managing breaking changes.

   Other ways it was asked

   • “How do you handle API versioning?”
   • “How do you ensure your API versioning doesn't disrupt existing clients, especially when making significant updates?”
   • “How do you version your API?”

3. How would you implement API versioning, and what would versioned endpoints look like?

   Asked in 3 of 377 interviews · last asked Oct 16 · Scenario · Mid-level

   Show answer

   I would put the major API version in the URL, such as `/api/v1/orders`, and route each version to its own handlers. I would add a new version for breaking changes and keep compatible changes in the current version. Old versions would stay available during a documented migration period.

   • URL paths are easy to see and test; headers or media types are alternatives.
   • Version both request and response contracts, not just endpoint names.
   • Test supported versions and announce retirement dates before removing old ones.

   CodeCopy

   GET /api/v1/orders/123
   POST /api/v1/orders
   GET /api/v2/orders/123
   POST /api/v2/orders

   What the interviewer checks: The interviewer is checking whether you can evolve an API without unexpectedly breaking existing clients.

   Other ways it was asked

   • “What steps would you follow to version an API?”
   • “How can you implement versioning in a Web API?”
   • “How can you implement API versioning, and what would a versioned GET or POST method look like?”

4. What is API versioning, and when would you use it?

   Asked in 2 of 377 interviews · last asked Sep 13 · Concept · Mid-level

   Other ways it was asked

   • “What is API versioning, and how would you use it?”

5. What is OpenAPI, and how is it used to describe APIs?

   Asked once · last asked Mar 9 · Concept · Junior

6. How do you document REST APIs and integrate them with other systems?

   Asked once · last asked Apr 9 · Scenario · Mid-level

7. When a front end calls a back-end API that triggers a long-running job, how would you design the API contract so the UI can reliably track progress, handle retries safely, and avoid duplicate work?

   Asked once · last asked Apr 17 · Design · Senior

8. How do you handle asynchronous requirements clarification when the Swagger spec conflicts with stakeholders' understanding?

   Asked once · last asked May 5 · Scenario · Senior

9. What is the Backend for Frontend (BFF) pattern, and when would you use it?

   Asked once · last asked May 11 · Concept · Mid-level

10. How would you roll out a schema change to the notification payload without breaking existing consumers?

    Asked once · last asked May 23 · Design · Senior

11. How would you structure the back-end API for notifications, including endpoints and data shapes, to support both real-time and paginated access?

    Asked once · last asked May 23 · Design · Senior

12. What are good practices for naming API endpoints?

    Asked once · last asked Jun 4 · Concept · Mid-level

13. What APIs should a billing system expose to support a mobile wallet integration?

    Asked once · last asked Jun 18 · Design · Senior

14. What does API-first mean, and how does the approach apply when working with existing products that already have APIs?

    Asked once · last asked Jun 18 · Concept · Senior

15. When you're designing endpoints and data models for a web application, how do you ensure that they're efficient and scalable for future growth?

    Asked once · last asked Jul 16 · Design · Mid-level

16. When you encounter mismatches between front-end TypeScript types and back-end API responses, how do you go about aligning them?

    Asked once · last asked Jul 11 · Scenario · Mid-level

17. What are the main components of an OpenAPI document?

    Asked once · last asked Jul 17 · Concept · Mid-level

18. How would you design API endpoints to create, delete, and update documents?

    Asked once · last asked Jul 27 · Design · Mid-level

19. How would you design paginated book endpoints and support partial updates with PATCH?

    Asked once · last asked Jul 28 · Design · Mid-level

20. What REST API endpoints would you design for a RAG pipeline?

    Asked once · last asked Jul 29 · Design · Mid-level

21. How can contract-change validation affect rollout speed and incident rates during a microservices migration?

    Asked once · last asked Jul 31 · Concept · Mid-level

22. In C#, how do you choose between an abstract class and an interface for a domain service contract, especially around versioning and default behavior?

    Asked once · last asked Aug 4 · Concept · Senior

23. When building RESTful APIs, what are your best practices for ensuring security, performance, and maintainability?

    Asked once · last asked Aug 10 · Concept · Senior

24. What API endpoints, schemas, and request flow would support ride requests, pickup, and drop-off?

    Asked once · last asked Aug 10 · Design · Mid-level

    Other ways it was asked

    • “What information should the rider and driver apps share through a REST API to fulfill a ride request?”
    • “What would the API schema look like for the rider and driver apps?”
    • “What API schema and flow would support requesting a ride, pickup, and drop-off?”

25. Where should a user notification endpoint live when platform clients need to notify their own end users about label status?

    Asked once · last asked Aug 11 · Design · Senior

26. What should an API response include for customers polling for label status?

    Asked once · last asked Aug 11 · Design · Mid-level

27. How would you version a public API without breaking existing clients, and what approach do you prefer?

    Asked once · last asked Aug 14 · Design · Senior

28. Why would you version a Web API, and what problem does versioning solve for API consumers?

    Asked once · last asked Aug 15 · Concept · Mid-level

29. What does Swagger or OpenAPI provide in an ASP.NET Core Web API project, and what are some key best practices that distinguish a production API from a basic CRUD API?

    Asked once · last asked Aug 15 · Concept · Mid-level

30. How do you approach designing a REST API to ensure it's both robust and easy for other developers to work with?

    Asked once · last asked Aug 20 · Design · Mid-level

31. When developing a REST API, what do you consider essential to make it consistent and production-ready?

    Asked once · last asked Aug 25 · Scenario · Mid-level

32. How do you go about building an API that is expected to evolve?

    Asked once · last asked Sep 3 · Design · Senior

33. What endpoints, request payloads, and responses would you define for a URL shortener API?

    Asked once · last asked Sep 8 · Design · Mid-level

    Other ways it was asked

    • “Can you define the content or contract for the create and get APIs for the URL shortener?”
    • “Define the API contract for the URL shortener—what endpoints and payloads do you need to start with?”

34. What potential issues would you look for in a URL shortener API design?

    Asked once · last asked Sep 8 · Scenario · Mid-level

35. What specific things do you systematically check in a PR with a README and API docs to catch naming inconsistencies, units, examples, and formatting before approving?

    Asked once · last asked Sep 8 · Scenario · Mid-level

36. When you spot a mismatch between API documentation and implementation, for example param name, casing, or response shape, what is your decision process for whether to change the code or the docs?

    Asked once · last asked Sep 8 · Scenario · Mid-level

37. In a PR where the docs specify GET /users/:userid returns last_login as an ISO-8601 string or null, but the code returns lastLogin and uses empty strings instead of null, what exact changes would you request and where?

    Asked once · last asked Sep 8 · Scenario · Mid-level

38. How do you approach API versioning in a large system: URI versus header versus media type, and how do you handle deprecation without breaking existing clients?

    Asked once · last asked Sep 10 · Design · Senior

39. How would you make a runbook or setup guide useful to others, and what would you look for when reviewing an API specification?

    Asked once · last asked Sep 20 · Behavioral · Mid-level

    Other ways it was asked

    • “Describe a runbook or setup guide you wrote, what it covered, and how it helped others. Also, what did you look for when reviewing an API specification?”

40. When reviewing an API specification, what do you check before flagging an issue?

    Asked once · last asked Sep 20 · Scenario · Mid-level

    Other ways it was asked

    • “When deciding whether to flag an issue in an API specification, what factors do you prioritize?”

41. What was the most important technical decision you made when defining an API contract, and why?

    Asked once · last asked Sep 21 · Behavioral · Mid-level

42. Tell me about a time an API contract changed and you had to adjust the frontend without breaking the user flow.

    Asked once · last asked Sep 21 · Behavioral · Mid-level

43. When an API contract changes, how do you coordinate deployment and maintain backward compatibility?

    Asked once · last asked Sep 21 · Scenario · Senior

    Other ways it was asked

    • “When an API contract changes, how do you coordinate deployment and reduce risks for older clients?”

44. How would you design service API contracts, handle versioning and backward compatibility, and prevent breaking changes?

    Asked once · last asked Sep 22 · Design · Senior

    Other ways it was asked

    • “How did you design service API contracts, handle versioning and backward compatibility, and prevent breaking changes?”

45. What edge API contract would you expose for a career search flow, and how would you validate requests and responses on both sides?

    Asked once · last asked Sep 22 · Design · Mid-level

    Other ways it was asked

    • “What API contract would you expose for a search flow, and how would you validate requests and responses on both sides?”

46. What is REST API contract versioning?

    Asked once · last asked Sep 23 · Concept · Mid-level

47. Why is API contract versioning important for teamwork?

    Asked once · last asked Sep 23 · Concept · Mid-level

48. What is the difference between oneOf and anyOf in OpenAPI?

    Asked once · last asked Sep 23 · Concept · Mid-level

49. What would you need to make an API genuinely useful for business decision-making?

    Asked once · last asked Oct 10 · Scenario · Senior

50. How do you define query parameters in Swagger?

    Asked once · last asked Oct 11 · Tooling · Junior

51. How would you design a minimal service for tracking and assigning deliveries?

    Asked once · last asked Oct 16 · Design · Mid-level

52. How would you expose a microservice so that 10 to 15 different consumers can use it?

    Asked once · last asked Oct 16 · Design · Mid-level

53. What is the difference between OData V2 and OData V4, and how would you convert an OData V2 service to V4 using CDS and Eclipse ADT?

    Asked once · last asked Oct 23 · Tooling · Senior

54. When building a new full stack feature with a React front end and a Node.js or Java back end, how do you version and evolve the API contract so older clients keep working while you deploy back end changes independently?

    Asked once · last asked Oct 24 · Design · Senior

    Other ways it was asked

    • “When building a new full stack feature with a React front end and a Node.js or Java back end, how do you version and evolve the API contract so older front end clients still work while the back end is deployed independently?”

55. In a microservices system, how do you document and govern cross service API contracts so teams can evolve independently without breaking consumers?

    Asked once · last asked Oct 24 · Design · Senior

56. When would you use a Student DTO in an application?

    Asked once · last asked Mar 30 · Concept · Junior

57. What is Swagger?

    Asked once · last asked Apr 8 · Concept · Junior

58. How do you document backend services and maintain the documentation frontend developers need?

    Asked once · last asked Apr 28 · Scenario · Mid-level

59. What factors do you consider when designing an API that is easy to use?

    Asked once · last asked May 19 · Concept · Mid-level

60. How do you document an API so the front-end team can understand its structure?

    Asked once · last asked Jun 23 · Scenario · Mid-level

61. What is a DTO?

    Asked once · last asked Jul 14 · Concept · Junior

62. What APIs does a URL shortener typically need?

    Asked once · last asked Sep 8 · Design · Mid-level

    Other ways it was asked

    • “What API endpoints do you need to create a URL shortener, specifically how do you generate the shortened URL?”

63. How do you maintain documentation for APIs?

    Asked once · last asked Sep 21 · Tooling · Mid-level

64. What is a structured output parameter when interacting with an AI model?

    Asked once · last asked Oct 13 · Concept · Mid-level

65. What API changes should be considered when migrating an application from Oracle to PostgreSQL?

    Asked once · last asked Oct 16 · Scenario · Mid-level

66. How do you choose the most appropriate API endpoint from the available paths?

    Asked once · last asked Oct 19 · Scenario · Mid-level

More REST API interview questions

• All REST API interview questions
• REST API Basics Interview Questions
• HTTP Methods and Status Codes Interview Questions
• REST API Implementation Interview Questions
• API Validation, Error Handling, and Testing Interview Questions
• REST API Security and Authentication Interview Questions
• API Pagination, Performance, and Rate Limiting Interview Questions
• API Idempotency, Retries, and Consistency Interview Questions
• API Integration and Webhooks Interview Questions

How this list is made

Every question here was asked by a real interviewer in a real job interview that a candidate ran MeetAssist in. After the call, the interviewer's questions are pulled from the transcript. Practice sessions, tests, exams and anything that was not a job interview are dropped.

Questions are rewritten so they make sense on their own: names of people, employers and clients are removed, and speech-to-text mistakes are fixed. Small talk, logistics and questions about one candidate's own résumé are left out. Rephrasings of the same question are merged, and the count is the number of different interviews it came up in.

The interviews come from candidates who use MeetAssist, so they lean towards software, data and AI roles: the shares describe these interviews, not every REST API interview. Answers to the most asked questions are written and checked by an editor; a "common mistake" is shown only when reviews of real answers in these interviews show it, with the count.

377 interviews, 243 candidates, Jan 2026 to Oct 2026. Updated every month with new interviews.