Published on Apr 07, 2025 5 min read

How to Use Postman for API Testing: A Complete Getting Started Guide

API development has become an essential part of modern web and app development. Whether it’s a social media app, an online store, or a weather app, APIs are the link between different systems and services. For those who are new to this field, working with APIs can feel complicated. However, a tool like Postman makes the process much easier.

Postman is a user-friendly tool used to build, test, and manage APIs. It allows developers, testers, and even beginners to send requests and receive responses without writing complicated code. This guide explains how to use Postman from a beginner’s perspective, helping users understand every step clearly.

What is Postman?

Postman is a free desktop and web-based tool that allows users to send API requests and view responses. It supports all common HTTP methods such as GET, POST, PUT, and DELETE. The tool helps in checking whether an API works as expected or not. Postman is widely used in software development teams for API testing, debugging, and automation. Using Postman is especially helpful for those learning how APIs work, as it provides a visual way to build and understand API requests.

Why Use Postman for API Development?

Postman is more than just a tool—it’s a complete API development platform. It offers several features that make the development process smooth, especially for beginners.

Key Advantages of Postman:

• Easy Interface: No coding knowledge is required to use the basic features.
• Request History: Postman saves all previous requests, making it easy to reuse or check past work.
• Collections: Users can organize API requests into folders for better management.
• Environments: Developers can create different settings for development, testing, or production.
• Built-in Testing Tools: Users can write simple tests to check if APIs are responding as expected.

Postman supports both solo work and team collaboration, making it useful for individual developers as well as large teams.

Installing and Setting Up Postman

To begin using Postman, users must first install it or use the web version.

Steps to Get Started:

1. Go to the official Postman website: https://www.postman.com/downloads/
2. Choose the version suitable for the user’s operating system (Windows, Mac, or Linux).
3. Download and install the application.
4. Create a free Postman account to save requests and access cloud features.

After logging in, users will see the Postman dashboard. It is the main area where requests are created, sent, and tested.

Understanding Key Terms in Postman

Before diving into requests, it’s helpful to understand a few important terms used in Postman.

• Request: The action is sent to an API to get or modify data.
• Response: The reply received from the API after making a request.
• Method: The type of action (GET, POST, PUT, DELETE).
• Endpoint: The specific URL that the API request is sent to.
• Headers: Additional information (such as authentication tokens) added to requests.
• Body: The data sent with the request (mainly for POST and PUT).
• Collection: A group of related API requests.
• Environment: Predefined variables used to make requests more dynamic.

These terms form the foundation of working with Postman.

Making the First API Request

To help beginners, Postman allows users to test public APIs without needing a server or writing code.

Example: Using a Free API

Let’s use a public API that returns random cat facts:

1. Open a new tab in Postman.
2. Choose the GET method from the dropdown menu.
3. In the URL field, enter:
   https://catfact.ninja/fact
4. Click the Send button.

Postman will return a JSON response containing a fun cat fact. It is a great way for beginners to see how requests and responses work.

Exploring Different Request Methods

Different types of HTTP methods are used based on what a user wants to do with the data.

Common Methods:

• GET: Used to fetch data from the server.
• POST: Sends new data to the server.
• PUT: Updates existing data.
• DELETE: Removes data from the server.

These methods are selected from the dropdown in the request tab. Understanding these actions helps users know how to interact with any API.

Organizing with Collections

Postman collections are folders where users can save and organize their API requests. This feature is especially useful for projects with many endpoints.

How to Create a Collection:

1. Click the Collections tab in the sidebar.
2. Click the “+ New Collection” button.
3. Name the collection and add a short description.
4. Save the collection and add requests to it for future use.

Collections help in grouping similar requests, which keeps work organized and easy to manage.

Using Parameters and Headers

In real-world APIs, requests often require parameters and headers.

Parameters:

• Used to pass data through the URL.
• Example:
  https://api.example.com/users?id=123

In Postman, parameters can be added under the Params tab.

Headers:

• Provide extra details such as content type or authentication tokens.
• Common header:
  Authorization: Bearer your_token_here

Headers can be added in the Headers tab in Postman. Understanding headers is important when working with secure or complex APIs.

Setting Up Environments and Variables

Postman allows the use of variables through environments, which can be helpful when switching between development, testing, and production setups.

Creating an Environment:

1. Click the gear icon on the top right.
2. Choose Manage Environments.
3. Create a new environment and add variables (like base_url = https://api.example.com).
4. Use variables in requests like this: {{base_url}}/users

This feature helps avoid rewriting URLs or tokens multiple times.

Running Requests with Collection Runner

Postman’s Collection Runner allows users to run several API requests one after another automatically.

How to Use It:

1. Open the desired collection.
2. Click the “Runner” button.
3. Select environment (if any).
4. Click Start Run.

It is useful when testing all endpoints before deploying an app or running repeatable tests during development.

Conclusion

API development no longer needs to be complicated for beginners. With Postman, users can explore, test, and manage APIs with ease—without writing any code. The tool’s clear interface, strong features, and flexibility make it one of the best platforms for API development and learning. By understanding basic methods, organizing requests into collections, using environments, and running simple tests, anyone can start working with APIs confidently. Postman not only helps beginners learn faster but also supports advanced features for future growth.