Infosys API Testing Interview Questions

Introduction – Why API Testing Is Important in Infosys Interviews

Infosys works on large-scale enterprise applications involving banking, insurance, telecom, retail, and digital platforms. In almost all these projects, APIs are the backbone connecting UI, backend services, databases, and third-party systems.

That’s why infosys api testing interview questions are a key part of:

• Technical screening rounds
  
• Project discussion rounds
  
• Client interview rounds
  

Interviewers at Infosys evaluate whether you:

• Understand API concepts clearly
  
• Can test backend logic without UI dependency
  
• Have hands-on experience with tools like Postman, SoapUI
  
• Can explain real-time API issues from projects
  
• Know basic API automation (for mid-level roles)
  

This article is a complete Infosys-focused guide with clear answers, real-time examples, JSON/XML samples, status codes, Postman scripts, and scenario-based questions.

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What Is API Testing? (Clear & Simple)

API testing is the process of verifying that Application Programming Interfaces work as expected by checking:

• Requests and responses
  
• Status codes
  
• Response data
  
• Headers and authentication
  
• Business logic and validations
  

Simple Example

For a login API:

• Valid credentials → 200 OK + token
  
• Invalid credentials → 401 Unauthorized
  
• Missing parameters → 400 Bad Request
  

Infosys interviewers expect you to explain what you validate beyond just the status code.

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REST vs SOAP vs GraphQL (Interview Comparison)

Feature	REST	SOAP	GraphQL
Protocol	HTTP	XML-based	HTTP
Data Format	JSON / XML	XML only	JSON
Performance	Fast	Slower	Optimized
Flexibility	High	Low	Very High
Usage at Infosys	Very High	Legacy projects	Limited

👉 REST APIs are most commonly asked in infosys api testing interview questions, while SOAP basics are useful for legacy projects.

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Infosys API Testing Interview Questions (90+ with Answers)

Section 1: API Basics (Q1–Q20)

1. What is an API?

An API allows different software systems to communicate with each other.

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2. What is API testing?

API testing validates backend services by checking requests, responses, headers, status codes, and business logic.

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3. Why is API testing important?

Because APIs are used by multiple applications, a single API defect can impact the entire system.

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4. Difference between API testing and UI testing?

API testing checks backend logic, while UI testing checks frontend behavior.

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5. Which APIs have you tested in your project?

Mostly REST APIs using Postman; some exposure to SOAP APIs.

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6. What HTTP methods have you used?

GET, POST, PUT, PATCH, DELETE.

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7. Difference between PUT and PATCH?

• PUT → Full update
  
• PATCH → Partial update
  

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8. What is an endpoint?

A specific URL representing an API resource, e.g. /customers/1001.

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9. What is request payload?

Data sent to the API in the request body.

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10. What is response body?

Data returned by the API after processing the request.

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11. What is stateless API?

Each request is independent and contains all required information.

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12. What is idempotency?

Repeating the same request multiple times gives the same result.

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13. What is API versioning?

Managing API changes using versions like /v1, /v2.

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14. What is authentication?

Verifying identity using token, API key, or credentials.

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15. What is authorization?

Verifying whether a user has access to a resource.

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16. What authentication types have you tested?

Bearer Token, Basic Auth, API Key.

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17. What is JWT?

JSON Web Token used for secure API authentication.

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18. What is API schema?

Defines structure and data types of request and response.

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19. What is API chaining?

Using response data from one API as input to another API.

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20. What is negative API testing?

Testing API behavior with invalid or unexpected inputs.

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HTTP Status Codes – Very Important for Infosys Interviews

Code	Meaning	Example
200	OK	Successful GET
201	Created	Successful POST
204	No Content	Successful DELETE
400	Bad Request	Invalid input
401	Unauthorized	Invalid token
403	Forbidden	Access denied
404	Not Found	Invalid endpoint
409	Conflict	Duplicate record
422	Unprocessable	Business rule failure
500	Server Error	Backend issue

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Section 2: API Validation & Testing Types (Q21–Q45)

21. What validations do you perform in API testing?

• Status code
  
• Response body
  
• Headers
  
• Schema
  
• Response time
  

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22. Is validating only status code enough?

No. Response data and business rules must be validated.

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23. What is positive API testing?

Testing APIs with valid input data.

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24. What is negative API testing?

Testing APIs with invalid data or missing parameters.

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25. What is boundary value testing?

Testing minimum and maximum allowed values.

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26. What is API regression testing?

Re-testing APIs after changes in code.

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27. What is API smoke testing?

Basic health check of APIs.

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28. What is API security testing?

Testing authentication, authorization, and data protection.

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29. What is API performance testing?

Testing response time and throughput.

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30. What is API rate limiting?

Restricting number of requests per user.

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31. What is pagination testing?

Validating page-wise data.

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32. What is filtering testing?

Validating query parameters.

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33. What is sorting testing?

Validating order of data in response.

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34. What is schema validation?

Ensuring response structure matches API contract.

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35. What is API mocking?

Simulating API responses when backend is unavailable.

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36. What is API rollback?

Reverting operations if failure occurs.

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37. What is data consistency testing?

Ensuring same data across systems.

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38. What is API concurrency testing?

Testing multiple requests at the same time.

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39. What is API caching?

Storing responses temporarily to improve performance.

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40. What is content-type validation?

Ensuring response format is JSON/XML.

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41. What is header validation?

Validating headers like Authorization and Content-Type.

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42. What is response time SLA?

Maximum acceptable response time.

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43. What is contract testing?

Validating agreement between API provider and consumer.

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44. What is API monitoring?

Tracking API uptime and failures.

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45. What is API throttling?

Limiting traffic to protect backend systems.

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Real-Time API Validation Example (Infosys Style)

Sample Request

POST /api/login

Content-Type: application/json

{

  “username”: “testuser”,

  “password”: “pass123”

}

Sample Response

{

  “token”: “abc.def.xyz”,

  “expires_in”: 3600,

  “userId”: 101

}

Validations Expected

• Status code = 200
  
• Token should not be null
  
• expires_in > 0
  
• userId should be numeric
  

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Postman & Automation Basics (Expected at Infosys)

Postman Test Script

pm.test(“Status code is 200”, function () {

  pm.response.to.have.status(200);

});

pm.test(“Token exists”, function () {

  var json = pm.response.json();

  pm.expect(json.token).to.not.be.undefined;

});

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Rest Assured (Java – Basic)

given()

  .contentType(“application/json”)

  .body(payload)

.when()

  .post(“/login”)

.then()

  .statusCode(200);

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Python Requests (Basic)

import requests

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

assert response.status_code == 200

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Scenario-Based Infosys API Testing Interview Questions (15)

These are commonly asked at Infosys:

1. API returns 200 but incorrect data – what do you validate?
   
2. Login API works, profile API fails – possible reasons?
   
3. Token expired but API still accessible – defect?
   
4. API works in Postman but fails in UI – why?
   
5. API slow only in production – possible causes?
   
6. Duplicate records created – what validation missed?
   
7. Unauthorized user accesses secured API – issue?
   
8. API crashes for special characters – what testing?
   
9. Same request returns different responses – why?
   
10. Payment deducted but order not created – what testing?
    
11. API returns null fields – how do you handle?
    
12. API response schema changes suddenly – impact?
    
13. API fails only in CI pipeline – possible reasons?
    
14. API returns XML instead of JSON – issue?
    
15. Partial data saved after failure – what testing missed?
    

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How Infosys Interviewers Evaluate Your Answers

Infosys interviewers focus on:

• Clear API fundamentals
  
• Real-time project examples
  
• Validation beyond status code
  
• Logical debugging approach
  
• Tool knowledge (Postman mandatory)
  

👉 Practical experience matters more than memorized answers.

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Infosys API Testing Interview Cheatsheet

• Always validate response body
  
• Never trust only 200 status
  
• Test negative scenarios
  
• Check headers and schema
  
• Understand authentication clearly
  
• Be ready with real project examples
  

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FAQs – Infosys API Testing Interview Questions

Q1. Is Postman mandatory for Infosys API testing roles?
Yes, Postman knowledge is expected.

Q2. Do I need automation knowledge for Infosys?
Basic automation knowledge is a plus.

Q3. REST or SOAP – which is more important?
REST is more important; SOAP basics help in legacy projects.

Q4. Biggest mistake candidates make?
Validating only status codes.

Q5. How should freshers prepare?
Practice APIs using Postman with real examples.