API testing is one of the most critical skills for any Software Quality Assurance (SQA) engineer. Modern applications rely heavily on APIs, making it essential for testers to validate functionality, performance, and security at the backend level.

In this tutorial, you’ll learn API testing using Postman—from beginner to advanced level with practical examples.

🧪 What is API Testing?

API (Application Programming Interface) testing focuses on verifying:

Data exchange between systems

Business logic

Response accuracy

Error handling

Unlike UI testing, API testing is faster, more reliable, and independent of frontend changes.

🛠️ What is Postman?

Postman is a popular tool used for:

Sending HTTP requests

Validating responses

Automating API tests

Managing collections