API Interview Questions Every Business Analyst Should Know (With Answers)

APIs play a major role in modern digital products. Whether it’s integrating two systems, improving data exchange, or supporting automation, Business Analysts (BAs) are often required to work closely with APIs—even if they’re not coding them. Understanding API fundamentals, use cases, and common interview questions can help you stand out in technical discussions and demonstrate strong analytical and integration skills.

Why Business Analysts Need API Knowledge

While BAs aren’t required to code APIs, they frequently work on projects involving system integrations.

Understanding how APIs work helps a BA:

• Write accurate BRDs, FRDs, user stories, and acceptance criteria
• Communicate effectively with developers, testers, and stakeholders
• Validate system behavior during UAT
• Analyze integration impacts during requirement changes
• Troubleshoot data flow issues across systems

API knowledge ultimately improves a BA’s ability to deliver precise, reliable requirements.

Top API Interview Questions Every Business Analyst Should Know

Below are the most common and practical API interview questions, grouped to help you prepare smoothly.

Question 1. What is an API?

Answer: An API (Application Programming Interface) is a set of rules that allows different software systems to communicate with each other. It defines how requests and responses should be structured so one system can use the functionality or data of another.

For a BA, understanding APIs is essential to explain integration points, data flow, and dependencies.

Question 2. What is a REST API?

Answer: A REST API is an architectural style where communication happens using standard HTTP methods like GET, POST, PUT, and DELETE. REST APIs often exchange data in JSON format, making them easy to read and integrate.

Question 3. What is JSON and why is it used in APIs?

Answer: JSON (JavaScript Object Notation) is a lightweight data format used widely in APIs because it’s readable, structured, and supported across most programming languages.

For BAs working on JSON API interview topics, understanding fields, nested objects, and arrays is important when writing requirements or validating API responses.

Example JSON:

{

  “id”: 101,

  “name”: “John”,

  “active”: true

}

Question 4. What’s the difference between SOAP and REST?

Answer:

REST is more common today, but some legacy systems still use SOAP.

Question 5. What is an Endpoint?

Answer: An endpoint is a specific API URL where the client sends a request.
Example: /users/123 retrieves user details.

As a BA, you’ll reference endpoints while documenting integration scenarios or test cases.

Question 6. How do you document API-related requirements?

Answer: A BA documents API requirements using:

• Integration requirements (input/output data)
• Request/response samples (JSON)
• Field-level definitions
• Error codes and handling
• System behavior when API fails
• Functional and non-functional requirements

This helps ensure clarity between development and QA teams.

Question 7. What is API testing and how do BAs support it?

Answer: API testing validates that the API behaves correctly.

BAs support it by:

• Preparing test scenarios and expected results
• Verifying API responses during UAT
• Helping testers understand business rules
• Checking if API output matches business logic

Tools like Postman make the process easier for non-developers.

Question 8. What is an API request vs. API response?

Answer:

• A request is what the client sends to the server (with method, headers, body).
• A response is what the server sends back (status code, JSON data).

This is central to many integration interview questions.

Question 9. What are Status Codes in APIs?

Answer: Common ones include:

• 200 – Success
• 201 – Created
• 400 – Bad Request
• 401 – Unauthorized
• 404 – Not Found
• 500 – Server Error

Knowing these helps a BA identify issues quickly.

Question 10. What is Authentication vs Authorization in APIs?

Answer:

• Authentication verifies identity
• Authorization determines access rights

BAs need this to write accurate security requirements

Question 11. What is Payload in API communication?

Answer: The payload is the actual data sent in the API request or response body.
Example: JSON user details in a POST request.

Question 12. What is Query Parameter vs Path Parameter?

Answer:

• Path parameter identifies a specific resource
  Example: /users/10
• Query parameter filters results
  Example: /users?status=active

This helps BAs design clear integration flows.

Question 13. What is an API Gateway?

Answer: An API gateway manages routing, security, throttling, and monitoring of APIs.
It’s important when working on large system integrations.

Question 14. What is Webhook and how is it different from API?

Answer: A webhook sends data automatically when an event occurs—no request required.
APIs require a request from the client.

Example:

• Webhook: “Notify me when payment succeeds.”
• API: “Request payment status whenever needed.”

Question 15. What are Idempotent Methods?

Answer: An idempotent method gives the same result no matter how many times it’s repeated.
Examples: GET, PUT, DELETE.

Conclusion

APIs are essential for modern Business Analysts, helping them manage integrations, document clear requirements, and collaborate effectively across teams. Strong API understanding improves project success and boosts confidence during technical interviews.