API Testing Framework Interview Questions

Introduction – Why API Testing Framework Knowledge Matters in Interviews

In modern QA and SDET interviews, knowing how to test APIs is no longer enough. Interviewers increasingly focus on API testing frameworks—how they are designed, structured, maintained, and scaled. That’s why api testing framework interview questions are common in both manual-to-automation transitions and experienced automation roles.

Interviewers want to see whether you can:

• Design a reusable and scalable API automation framework
  
• Separate test logic from test data
  
• Handle authentication, assertions, and reporting
  
• Integrate API tests with CI/CD pipelines
  

This article is a complete interview preparation guide covering framework concepts, tools, real-time examples, code snippets, and scenario-based REST API testing questions—suitable for freshers to experienced professionals.

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What Is API Testing? (Clear & Simple)

API testing is the process of validating Application Programming Interfaces by sending requests and verifying responses for correctness, performance, security, and reliability—without involving the UI.

In one line:

API testing ensures that backend services and business logic work correctly.

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REST vs SOAP vs GraphQL

Feature	REST	SOAP	GraphQL
Type	Architectural style	Protocol	Query language
Data format	JSON	XML	JSON
Performance	Fast & lightweight	Slower	Optimized
Flexibility	High	Low	Very high
Usage	Most modern apps	Legacy/enterprise apps	Modern frontend apps

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90+ API Testing Framework Interview Questions & Answers

API Testing Framework Basics (Freshers)

1. What is an API testing framework?
   A structured setup of tools, libraries, utilities, and standards used to automate API testing efficiently.
   
2. Why do we need an API testing framework?
   To improve reusability, maintainability, scalability, and reduce duplication.
   
3. What are the core components of an API framework?
   Request handling, assertions, test data management, reporting, and configuration.
   
4. Which APIs are easiest to automate in frameworks?
   REST APIs.
   
5. What protocols are commonly used?
   HTTP and HTTPS.
   
6. What is an endpoint?
   A URL where an API receives requests.
   
7. What is request payload?
   Data sent to the server in POST/PUT/PATCH requests.
   
8. What is response payload?
   Data returned by the server.
   
9. What is statelessness in REST?
   Each request is independent and contains all required data.
   
10. What is idempotency?
    Multiple identical requests produce the same result.
    

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REST API Framework Interview Questions

11. Which HTTP methods are commonly used?
    GET, POST, PUT, PATCH, DELETE.
    
12. Difference between GET and POST?
    GET retrieves data; POST creates data.
    
13. Difference between PUT and PATCH?
    PUT replaces a resource; PATCH updates part of it.
    
14. What is JSON?
    A lightweight data-interchange format.
    

{

  “id”: 101,

  “name”: “Srushti”,

  “role”: “QA Engineer”

}

15. What are headers in API frameworks?
    Metadata like Content-Type and Authorization.
    
16. What is Content-Type?
    Specifies request/response format (application/json).
    
17. What is a query parameter?
    Parameter passed after ? in the URL.
    
18. What is a path parameter?
    Dynamic value inside the endpoint path.
    
19. What is pagination?
    Splitting large data into pages.
    
20. What is API versioning?
    Managing changes using /v1, /v2, or headers.
    

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API Testing Framework Design Questions

21. What design pattern is commonly used in API frameworks?
    Layered or service-based architecture.
    
22. How do you separate test logic and test data?
    Using external files (JSON, Excel, YAML).
    
23. How do you handle configuration in frameworks?
    Using properties or config files.
    
24. How do you manage environments (QA, Staging, Prod)?
    Environment-specific config files or variables.
    
25. How do you handle authentication in frameworks?
    Centralized token generation utilities.
    
26. How do you reuse API methods?
    By creating reusable service classes.
    
27. How do you implement assertions?
    Centralized assertion utilities.
    
28. How do you log API requests and responses?
    Using logging libraries or framework hooks.
    

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API Automation Tools Interview Questions

29. Which tools are used to build API testing frameworks?
    Postman, SoapUI, Rest Assured, Karate, Python requests.
    
30. What is Postman used for in frameworks?
    Manual validation, collection-based automation, and CI execution.
    
31. What is SoapUI used for?
    Functional, regression, and security testing.
    
32. What is Rest Assured?
    A Java-based library for REST API automation.
    
33. Which language is Rest Assured based on?
    Java.
    
34. What is Karate framework?
    A BDD-style API automation framework.
    
35. Can API frameworks run without UI tests?
    Yes, API frameworks are UI-independent.
    

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SOAP & XML Framework Questions

36. Can SOAP APIs be automated in frameworks?
    Yes, using XML requests and XPath assertions.
    
37. What is WSDL?
    XML document describing SOAP services.
    

<response>

  <status>SUCCESS</status>

</response>

38. How do you validate XML responses?
    Using XPath or schema validation.
    

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HTTP Status Codes – Must Know

Status Code	Meaning
200	OK
201	Created
204	No Content
400	Bad Request
401	Unauthorized
403	Forbidden
404	Not Found
409	Conflict
500	Internal Server Error

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Real-Time API Validation Example

Request

POST /api/users

Payload

{

  “email”: “test@example.com”,

  “password”: “Test@123”

}

Response

{

  “id”: 501,

  “message”: “User created successfully”

}

Validations

• Status code = 201
  
• id is not null
  
• Message equals expected text
  

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Automation Code Snippets (Framework-Style)

Postman Test Script

pm.response.to.have.status(201);

pm.expect(pm.response.json().id).to.exist;

Rest Assured (Java)

given()

  .when()

  .post(“/api/users”)

  .then()

  .statusCode(201);

Python API Automation

import requests

response = requests.post(url, json=payload)

assert response.status_code == 201

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Scenario-Based API Testing Framework Interview Questions (10+)

51. API returns 200 but wrong data. What do you do?
    Add business-level assertions and raise a defect.
    
52. How do you handle dynamic tokens in frameworks?
    Generate tokens using utility methods and reuse them.
    
53. How do you test dependent APIs in frameworks?
    Chain requests using extracted values.
    
54. How do you automate negative scenarios?
    Data-driven tests with invalid inputs.
    
55. How do you validate response schemas?
    Use JSON/XML schema validation.
    
56. How do you test rate limiting?
    Send multiple requests and assert 429 response.
    
57. How do you validate API performance in frameworks?
    Assert response time thresholds.
    
58. How do you handle flaky API tests?
    Improve assertions and add retries where needed.
    
59. How do you integrate API frameworks with CI/CD?
    Run tests using Maven/Gradle in pipelines.
    
60. How do you debug failing API tests?
    Log requests, headers, payloads, and responses.
    

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How Interviewers Evaluate Your Answers

Interviewers evaluate:

• Understanding of API fundamentals
  
• Knowledge of framework design principles
  
• Ability to explain real-time scenarios
  
• Proper use of assertions and utilities
  
• Clean, logical explanations
  

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API Testing Framework Cheat Sheet (Quick Revision)

• Reusable service classes
  
• Centralized configuration
  
• Data-driven testing
  
• Strong assertions
  
• Token management
  
• CI/CD integration
  

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FAQs – API Testing Framework Interview Questions

Q1. Are API testing frameworks mandatory for automation roles?
Yes, especially for SDET and automation positions.

Q2. Is Rest Assured enough to build a framework?
Yes, with proper structure and utilities.

Q3. Can freshers learn API frameworks easily?
Yes, REST frameworks are beginner-friendly.

Q4. Are REST APIs more common than SOAP in frameworks?
Yes, REST APIs dominate modern frameworks.