Introduction

Hey software testers! What’s up? As the demand of API (Application programming Interfaces) increases by clients to make their applications robust, reliable and fast-paced, so it’s become crucial for the developers and testers to make APIs working smoothly and seamlessly in any circumstances. APIs are used on web apps, mobile apps, desktop apps, and microservice architecture, so it’s very important to test them before deploying to the client side.

While automation is great, manual API testing remains a powerful way to understand your API’s behavior and spot issues early. If you're just getting started, tools like Postman and platforms like Apyflux can make the process smoother and more effective.

In this blog we are going to explain the basics of manual API testing using Postman. Here you can find the details from setup of the testing tool to best practices. Read the articles till below to get detailed knowledge of each step.

What is API Testing?

Before diving into tools, let’s clarify what API testing is all about. At its core, It's a type of software testing that mainly focuses on verifying whether an application programming interface (API) works correctly, reliably, securely, and performs as expected. In simple words, API testing is whether the communication between software is happening correctly or not.

This includes checking:

• Response status codes
• Response time
• Data accuracy
• Error handling
• Authentication and security

Unlike UI testing, API testing focuses purely on the data layer, making it faster and more reliable.

There are two types of API testing: manual and automated. Manual testing is perfect when you’re in the early stages of development, exploring new endpoints, or debugging an issue. And for that, Postman is the go-to tool.

What is Postman and Why Should You Use It?

If you've ever searched "how to use Postman" online, you're not alone. Postman is one of the most popular tools for testing APIs manually. It has a clean interface, great documentation features, and allows you to quickly send HTTP requests without writing any code.

Here’s why beginners love Postman:

• Easy to install and use
• Supports all HTTP methods (GET, POST, PUT, DELETE, etc.)
• Allows saving and organizing test cases in collections
• Has built-in testing and scripting capabilities
• Free to get started

In short, if you’re looking for a no-fuss introduction to manual API testing, Postman is your best friend.

How to Set Up Postman for API Testing

Let’s break it down step-by-step:

1. Download and Install Postman

• Head over to https://www.postman.com/downloads/ and download the appropriate version for your operating system.
• Installation takes just a few minutes.

2. Create Your First API Request

• Once installed, launch Postman and click on "New" > "Request".
• Name your request and save it to a new collection for better organization.

Let’s test a simple GET request:

• URL: [https://jsonplaceholder.typicode.com/posts/1] (https://jsonplaceholder.typicode.com/posts/1)
• Click Send

You should see a JSON response with post details. Congrats! You’ve just made your first API call using Postman.

3. Understanding Request Components

• Headers: Key-value pairs for metadata (like Content-Type, Authorization)
• Params: For sending query strings like ?id=1
• Body: Used in POST/PUT requests to send data
• Response: Where you analyze the API’s reply

Getting comfortable with these parts will help you test APIs efficiently.

Step-by-Step Manual API Testing with Postman

Now that you’ve got the basics, let’s test an example API, like a login system.

Example: Login API (POST)

• Endpoint: https://api.example.com/login

• Method: POST

• Headers:

  • Content-Type: application/json

Body:

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{
  "email": "user@example.com",
  "password": "password123"
}

Steps:

1. Enter the URL and set the method to POST.

2. Add required headers.

3. Switch to the Body tab, select raw and choose JSON.

4. Paste the JSON request body.

5. Click Send.

What to look for in the response:

• Status Code: Should be 200 OK for successful login.
• Body: Should include a success message or token.
• Response Time: Should be under 500ms ideally.

You can also explore POST, PUT, DELETE, and other methods to simulate real-world scenarios.

API Testing Best Practices

Manual API testing isn’t just about clicking “Send.” Here are some API testing best practices to follow:

1. Validate Status Codes

Ensure the API returns the correct HTTP codes like 200, 400, 401, 404, or 500.

2. Test Positive and Negative Scenarios

Always test with both valid and invalid data to see how the API behaves under stress.

3. Use Environment Variables

Postman lets you store variables (like base URLs, tokens) to switch between environments (dev, staging, production) easily.

4. Save and Organize with Collections

Group related requests into collections. This makes collaboration and version tracking easier.

5. Automate Where It Makes Sense

You can use Postman’s Tests tab to write simple scripts for validation.

Example:

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

Even in manual testing, a little scripting can go a long way.

Simplify API Testing Further with Apyflux

As you grow more comfortable with manual API testing, you might want to streamline your workflow. That’s where Apyflux comes in.

What is Apyflux?

Apyflux is a modern API testing and monitoring platform that simplifies how developers and QA engineers test APIs.

Unlike traditional tools, Apyflux offers advanced features like:

• Real-time monitoring of API health
• Automated test scheduling
• Smart documentation and versioning
• Better collaboration tools than basic tools offer

You can even integrate Apyflux into CI/CD pipelines, making it a great companion for manual testing that scales.

Why Use Apyflux?

While Postman is great for getting started, Apyflux helps you grow. You’ll find it especially useful for team-based projects, long-term testing, and integrating manual and automated workflows seamlessly.

Common Mistakes in Manual API Testing (and How to Avoid Them)

Everyone makes mistakes when starting out. Here are a few to avoid:

• Not testing edge cases (like empty inputs or invalid tokens)
• Ignoring response time
• Hardcoding values instead of using variables
• Overlooking version control or test documentation
• Not collaborating or sharing test collections

The good news? All of these can be avoided with a little awareness and the right tools.

Conclusion

Manual API Testing must be basic skills to all software developers, testers, and tech enthusiasts. Testers can find the basic tools like Postman that makes easy testing for APIs. Apyflux-like platforms can also facilitate testing facilities for basic testing of APIs.

Whether you’re debugging an endpoint, exploring a new API, or testing your app's backend, remember to follow API testing best practices and keep learning.

So go ahead—download Postman, test your first API, and see the magic of clean communication between software systems. In this blog we have explained about the basic manual api testing using Postman like testing tools.