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Home › API Testing Interview Questions
Study Material

API Testing Interview Questions Downloads

This page lists Uncodemy's API Testing interview question resources, each as its own file. API testing interviews usually cover HTTP methods and status codes, authentication, validating responses, negative testing and tools such as Postman or REST Assured. Sample questions with short answers are below.

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Prepared by: Uncodemy trainer team · Reviewed by: Uncodemy reviewer · Last reviewed: 24 Oct 2026
Downloads

Download API Testing Interview Questions

Each resource is a separate file. Choose the one that matches what you need.

01
Set 1

API Testing Interview Questions — Core Set

Covers HTTP methods, status codes, authentication and response validation for interview preparation.

Updated 24 Oct 2026
Download Set 1
02
Set 2

API Testing Interview Questions — Advanced Set

Covers negative testing, edge cases, idempotency and tools such as Postman and REST Assured.

Updated 24 Oct 2026
Download Set 2
03
Set 3

API Testing Interview Questions — Practice Set

Practice-oriented questions with short answers, useful for revision before interviews.

Updated 24 Oct 2026
Download Set 3
Interview Focus

What interviewers usually probe

These are the areas most API testing interviews return to.

  • HTTP methods, status codes and headers.
  • Authentication and authorisation.
  • What you validate beyond the status code.
  • Negative and edge-case testing.
  • Tools, automation and CI.
Sample Q&A

Sample API testing interview questions

Short, practical answers you can revise quickly.

1 What is the difference between PUT and PATCH?

PUT replaces a resource with the data sent, while PATCH applies a partial update to some fields. PUT is idempotent; PATCH may or may not be, depending on how it is implemented.

2 What do 401 and 403 mean?

401 Unauthorized means authentication is missing or invalid. 403 Forbidden means the caller is authenticated but not allowed to perform the action.

3 What would you validate in an API response besides the status code?

The response body fields and data types, the schema, headers such as content type, response time, error messages for invalid input, and that the data matches what the system stored.

4 What negative tests would you write for a create-user endpoint?

Missing required fields, invalid formats, duplicate values, oversized input, wrong content type, missing or expired authentication, and unauthorised roles.

5 What is idempotency?

An operation is idempotent if repeating it gives the same result. GET, PUT and DELETE are meant to be idempotent, while POST usually is not.

Preparation

Preparation tips

Small habits that make interview prep smoother.

J

Practice JSON

Read and write JSON confidently — request bodies and response structures.

C

Explain a collection

Be ready to explain a collection or suite you built and why you structured it that way.

T

Chain requests & tokens

Know how to chain requests and manage tokens in a real workflow.

Related

Related Uncodemy resources

API Testing Guide Postman API Testing Guide Selenium Interview Questions AI Testing Interview Questions

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Prefer guided learning? Explore the Software Testing course or ask for a free demo.

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About this study material

This material is for learning and revision. It is not a certificate, a degree or a promise of a job, and technology changes, so check official documentation for the latest details. Spot an error? Write to info@uncodemy.com and the trainer team will review it.

FAQ

Frequently Asked Questions

What are common API testing interview questions?
Common topics are HTTP methods, status codes, authentication, response validation, negative testing, idempotency and tools such as Postman or REST Assured.
What is the difference between 401 and 403?
401 means authentication is missing or invalid. 403 means the user is authenticated but does not have permission.
What is the difference between PUT and POST?
POST usually creates a resource and is not idempotent. PUT replaces a resource at a known address and is idempotent.
How do I test API authentication?
Test valid credentials, missing and invalid credentials, expired tokens and users with insufficient permissions, and check the correct status codes are returned.
Are these questions from real company interviews?
No. They are written to cover common concepts. We do not claim any specific company asked them.
Are these resources free to download?
The download cards on this page link directly to the files. Use the button on the card that matches what you need.