Top REST API Automation Tester Interview Questions & Answers

API testing plays a crucial role in software development, ensuring the reliability and performance of backend services. If you're preparing for a REST API Automation Tester job interview, this blog will help you ace it with 60+ essential interview questions.

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1. General API & REST Basics

1. What is an API?
2. What is RESTful API?
3. What are the HTTP methods used in REST API?
4. What is the difference between PUT and POST?
5. What are HTTP status codes? Can you explain some commonly used ones?
6. What are request and response headers in REST APIs?
7. What is JSON, and why is it used in REST APIs?
8. What is the difference between SOAP and REST?
9. What are idempotent HTTP methods?
10. What are query parameters and path parameters in REST API?

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2. API Testing Concepts

11. What is API testing, and why is it important?
12. What are the key differences between API testing and UI testing?
13. What are different types of API testing?
14. What is contract testing in APIs?
15. What is schema validation in API testing?
16. What is API mocking, and when is it used?
17. What is the role of Postman in API testing?
18. How do you validate response payloads in API testing?
19. What is an API gateway?
20. What is rate limiting in APIs?

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3. REST Assured & Automation Framework

21. What is Rest Assured?
22. How do you set up Rest Assured in a Maven project?
23. What are the advantages of using Rest Assured over Postman?
24. Can you write a simple GET request using Rest Assured?
25. How do you pass headers, query parameters, and body in a Rest Assured request?
26. How do you validate JSON response fields using Rest Assured?
27. What is the use of Response and Extract in Rest Assured?
28. How do you handle authentication in Rest Assured (Basic Auth, Bearer Token, OAuth)?
29. How do you handle dynamic data in API tests using Rest Assured?
30. How do you implement data-driven testing in API automation?

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4. TestNG & JUnit

31. What is the difference between TestNG and JUnit?
32. What are annotations in TestNG?
33. How do you define dependencies in TestNG?
34. How do you run multiple API tests in parallel using TestNG?
35. What is a TestNG XML file, and how is it used?
36. What is the difference between @BeforeMethod and @BeforeClass in TestNG?
37. How do you generate TestNG reports for API tests?
38. How do you perform assertions in TestNG for API responses?
39. What is a Test Listener in TestNG?
40. How do you retry failed tests in TestNG?

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5. Performance & Security Testing

41. What tools do you use for API performance testing?
42. How do you test API load using JMeter or Gatling?
43. What are security vulnerabilities in REST APIs?
44. How do you test API security (JWT, OAuth, API key, etc.)?
45. What is CORS (Cross-Origin Resource Sharing) in APIs?
46. What is SQL injection, and how do you prevent it in APIs?
47. How do you test for API rate limiting and throttling?
48. How do you handle API timeouts and retries in automation?
49. What is API monitoring, and how do you implement it?
50. What is penetration testing in API security?

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6. CI/CD & DevOps Integration

51. How do you integrate API tests with Jenkins?
52. How do you trigger API tests in a CI/CD pipeline?
53. What are Docker and Kubernetes, and how are they used in API testing?
54. How do you handle environment-specific API testing (dev, QA, production)?
55. How do you use GitHub Actions for API test automation?

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7. Real-World Scenarios

56. How do you handle API dependencies when testing microservices?
57. How do you mock external APIs in automation?
58. How do you test APIs that require authentication?
59. What are the challenges you faced in API automation?
60. How would you test an API with limited documentation?

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Conclusion

Mastering these questions will help you crack your API automation testing interview with confidence. If you have experience with REST Assured, TestNG, and CI/CD integrations, make sure to highlight those skills in your responses.

Let me know in the comments if you'd like detailed answers for any of these questions! 🚀

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