Exploring Postman

When I first heard the term API testing, I had no idea what it meant. I was learning manual testing and exploring tools like JIRA and Agile Central, but APIs felt like something only developers dealt with. Still, I was curious. I kept hearing how important API testing is—especially for automation testers—and I wanted to understand it for myself. So I decided to start small. No pressure, no fancy setups—just a simple goal: figure out what an API is and how to test it.

🧠 Understanding APIs:

I started by reading about APIs online. The explanation that clicked for me was this:
An API is like a messenger between two software systems.
It lets one application talk to another. For example, when you use a weather app, it doesn’t generate the weather—it fetches it from a server using an API.

That made sense. But how do you test something that’s invisible? That’s where I discovered Postman.

🛠️ Discovering Postman

Postman kept popping up in tutorials and forums. People said it was beginner-friendly, so I downloaded it from postman.com and started exploring.

At first, the interface looked overwhelming—tabs, headers, body, params—but I took it one step at a time. I created a free account and opened a new request. I didn’t know what to test, so I Googled “free APIs for practice” and found JSONPlaceholder.

My first test was a GET request to this URL:
https://jsonplaceholder.typicode.com/posts/1

I clicked Send, and boom—there was a response! A bunch of JSON data appeared on the screen. It felt like magic. I had just fetched data from a server using an API.

🔍 Learning About Requests and Responses

Once I got comfortable with GET requests, I wanted to understand other types:

POST: Used to send data to the server (like submitting a form)
PUT: Used to update existing data
DELETE: Used to remove data

I tried sending a POST request with a sample payload:

{
  "title": "Hello API",
  "body": "This is my first POST request",
  "userId": 1
}

I added this to the Body tab in Postman, selected raw and JSON, and hit Send. The response showed the data I had sent, along with a new ID. That was exciting—I was interacting with the API like a real user!

I also learned to check the status codes:

200 OK means success
201 Created means a new resource was made
404 Not Found means the endpoint doesn’t exist
500 Internal Server Error means something went wrong on the server

🧪 Testing Payloads and Edge Cases

As I practiced more, I started experimenting with different payloads—changing values, leaving fields empty, sending invalid data. I wanted to see how the API would respond. Would it reject the request? Would it return an error?

Postman made it easy to test all these scenarios. I didn’t need to write any code—I just changed the input and observed the output.

I also explored the Tests tab in Postman, where you can write simple JavaScript to validate responses. For example:

pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});

This helped me automate basic checks and understand how testing logic works.

🌱 What I’ve Learned So Far

Looking back, I’m glad I started learning API testing through Postman. It taught me:

How APIs work behind the scenes
How to send different types of requests (GET, POST, PUT, DELETE)
How to read and understand responses
How to test payloads and handle edge cases
How to write basic tests to validate responses

Most importantly, it gave me confidence. I no longer feel lost when someone mentions APIs or backend testing. I know how to test endpoints, analyze responses, and contribute meaningfully to a testing team.

🌟 Final Thoughts

If you’re just starting out in testing, don’t be afraid of APIs. You don’t need to be a developer to understand them. Tools like Postman make it easy to learn by doing. Start with simple requests, explore free APIs, and build your understanding step by step.

API testing isn’t just a skill—it’s a superpower for testers. And Postman is the perfect place to begin your journey.