🚀 Smart Summary Postman is a scalable API testing tool designed for efficient API workflow management in development and testing environments. It enables streamlined organization, collaboration, and automation, making critical API testing tasks accessible and repeatable. Key Principle: Postman provides a unified workspace for API request creation, testing, and management, supporting both manual and automated testing workflows. Implementation Focus: Organize requests into collections, which can be further subdivided into folders and shared easily among team members for efficient collaboration. Parameterization Rule: Use environment and global variables with double curly brackets (e.g., {{url}}) to parameterize requests, reducing redundancy and enabling reuse across multiple API endpoints. Testing Essentials: Write JavaScript-based tests in the Tests tab to validate status codes, response bodies, and expected values, ensuring robust API coverage and reliability. Automation Path: Run collections via the Collection Runner or Newman, the latter being essential for CI/CD integration and automated batch execution using command-line interfaces. What is Postman? Postman is a scalable API testing tool that quickly integrates into a CI/CD pipeline. It started in 2012 as a side project by Abhinav Asthana to simplify API workflow in testing and development. API stands for Application Programming Interface, which allows software applications to communicate with each other via API calls. 👉 Enroll for Free Live API Testing Project Why Use Postman? With over 4 million users nowadays, Postman Software has become a tool of choice for the following reasons: Accessibility – To use the Postman tool, one would just need to log in to their own accounts, making it easy to access files anytime, anywhere, as long as a Postman application is installed on the computer. Use of Collections – Postman lets users create collections for their Postman API calls. Each collection can create subfolders and multiple requests. This helps in organizing your test suites. Collaboration – Collections and environments can be imported or exported, making it easy to share files. A direct link can also be used to share collections. Creating Environments – Having multiple environments aids in less repetition of tests, as one can use the same collection but for a different environment. This is where parameterization will take place, which we will discuss in further lessons. Creation of Tests – Test checkpoints, such as verifying for successful HTTP response status, can be added to each Postman API calls, which help ensure test coverage . Automation Testing – Through the use of the Collection Runner or Newman, tests can be run in multiple iterations, saving time for repetitive tests. Debugging – Postman console helps to check what data has been retrieved, making it easy to debug tests. Continuous Integration – With its ability to support continuous integration, development practices are maintained. How to use Postman to execute APIs Below is the Postman Workspace. Let’s explore the step-by-step process on How to use Postman and different features of the Postman tool! New – This is where you will create a new request, collection, or environment. Import – This is used to import a collection or environment. There are options such as import from file, folder, link, or paste raw text. Runner – Automation tests can be executed through the Collection Runner. This will be discussed further in the next lesson. Open New – Open a new tab, Postman Window, or Runner Window by clicking this button. My Workspace – You can create a new workspace individually or as a team. Invite – Collaborate on a workspace by inviting team members. History – Past requests that you have sent will be displayed in History. This makes it easy to track actions that you have done. Collections – Organize your test suite by creating collections. Each collection may have subfolders and multiple requests. A request or folder can also be duplicated. Request tab – This displays the title of the request you are working on. By default, “Untitled Request” would be displayed for requests without titles. HTTP Request – Clicking this would display a dropdown list of different requests, such as GET, POST, COPY, DELETE, etc. In Postman API testing, the most commonly used requests are GET and POST. Request URL – Also known as an endpoint, this is where you will identify the link to which the API will communicate. Save – If there are changes to a request, clicking save is a must so that new changes will not be lost or overwritten. Params – This is where you will write parameters needed for a request, such as key values. Authorization – In order to access APIs, proper authorization is needed. It may be in the form of a username and password, a bearer token, etc. Headers – You can set headers such as content type JSON, depending on the needs of the organization. Body – This is where one can customize details in a request, commonly used in a POST request. Pre-request Script – These are scripts that will be executed before the request. Usually, pre-request scripts for the setting environment are used to ensure that tests will be run in the correct environment. Tests – These are scripts executed during the request. It is important to have tests as it sets up checkpoints to verify if the response status is ok, retrieved data is as expected, and other tests. Working with GET Requests Get requests are used to retrieve information from the given URL. There will be no changes made to the endpoint. We will use the following URL for all examples in this Postman tutorial https://jsonplaceholder.typicode.com/users In the workspace Set your HTTP request to GET. In the request URL field, input the link You will see a “200 OK” Message There should be 10 user results in the body, which indicates that your test has run successfully. *Note: There may be cases where the Get Postman request may be unsuccessful. It can be due to an invalid request URL, or authentication is needed. Top 47 Postman Interview Questions and Answers (2026) How to Download & Install Postman for Windows? Working with POST Requests Post requests are different from Get requests as there is data manipulation with the user adding data to the endpoint. Using the same data from the previous tutorial in Get request, let’s now add our own user. Step 1) Click a new tab to create a new request. Step 2) In the new tab Set your HTTP request to POST. Input the same link in request url: https://jsonplaceholder.typicode.com/users switch to the Body tab Step 3) In Body, Step 4) Copy and paste just one user result from the previous get request like below. Ensure that the code has been copied correctly with paired curly braces and brackets. Change id to 11 and name to any desired name. You can also change other details like the address. *Note: Online Post request should have the correct format to ensure that the requested data will be created. It is a good practice to use Get first to check the JSON format of the request. You can use tools like https://jsonformatter.curiousconcept.com/ Status: 201 Created should be displayed Posted data are showing up in the body. How to Parameterize Requests Data Parameterization is one of the most useful features of Postman. Instead of creating the same requests with different data, you can use variables with parameters. These data can be from a data file or an environment variable. Parameterization helps to avoid repetition of the same tests, and iterations can be used for automation testing . Parameters are created through the use of double curly brackets: {{sample}}. Let’s take a look at an example of using parameters in our previous request: Now let’s create a parameterized GET request. Set your HTTP request to GET Input this link: https://jsonplaceholder.typicode.com/users . Replace the first part of the link with a parameter such as {{url}}. Request url should now be {{url}}/users. There should be no response since we have not set the source of our parameter. Step 2) To use the parameter you need to set the environment Click the eye icon Click edit to set the variable to a global environment, which can be used in all collections. Step 3) In variable, set the name to the url which is https://jsonplaceholder.typicode.com Step 4) Click close if you see the next screen Step 5) Go back to your Get request, then click send. There should now be results for your request. *Note: Always ensure that your parameters have a source, such as an environment variable or data file, to avoid errors. How to Create Postman Tests Postman Tests are JavaScript codes added to requests that help you verify results, such as successful or failed status, comparison of expected results, etc. It usually starts with pm.test. It can be compared to asserts, verify commands available in other tools. Let’s do some basic API testing using Postman for our parameterized requests from the previous lesson. Step 1) Go to your GET user request from the previous tutorial. Switch to the tests tab. On the right side are snippet codes. From the snippets section, click on “Status code: Code is 200”. The pane is auto-populated Step 2) Now click Send. The test result should now be displayed. Step 3) Go back to the test tab and let’s add another test. This time we will compare the expected result to the actual result. From the snippets section, click on “Response body:JSON value check”. We will be checking if Leanne Graham has the userid 1. Replace “Your Test Name” from the code with “Check if user with id1 is Leanne Graham” so that the test name specifies exactly what we want to test. Replace jsonData.value with jsonData[0].name. To get the path, check the body in Get result earlier. Since Leanne Graham is userid 1, jsonData is in the first result, which should start with 0. If you want to get the second result, use jsonData[1] and so on for succeeding results. In to eql, input “Leanne Graham” Step 5) Click send. There should now be two passed test results for your request. *Note: There are different kind of tests that can be created in Postman. Try to explore the tool and see what tests will fit your needs. How to Create Collections Collections play an important role in organizing test suites. It can be imported and exported, making it easy to share collections amongst the team. In this tutorial, we will learn how to create and execute a collection. Let’s start in creating a collection: Step 1) Click on the New button at the top left corner of the page. Step 2) Select Collection. Create collection window should pop up. Step 3) Input the desired collection name and description then click create. A collection should now be created.

Step 4) Go back to the previous Get request. Click Save Select Postman Test Collection. Click Save to Postman Test Collection Step 6) Postman test collection should now contain one request. Step 7) Repeat steps 4-5 for the previous Post request so that the collection will now have two requests. How to Run Collections using Collection Runner There are two ways to run a collection which is the Collection Runner and Newman. Let’s begin by executing the collection in Collection Runner. Step 1) Click on the Runner button found at the top of the page next to the Import button. Step 2) Collection Runner page should appear such as below. Following is the description of various fields Step 3) Run your Postman Test Collection by setting up the following: Choose Postman test collection- Set iterations as 3 Set delay as 2500 ms Click on Run Postman Test… button Step 4) Run Results page should be displayed after clicking the Run button. Depending on the delay, you should see the tests as they execute. Once tests have finished, you can see the test status if it is Passed or Failed and the results per iteration. You see Pass status for the Get Requests Since we did not have any tests for Post, there should be a message that the request did not have any tests. You can see how important it is that there are tests in your requests so that you can verify HTTP request status if successful and the data is created or retrieved. How to Run Collections using Newman Another way to run a collection is via Newman. The main differences between Newman and Collection Runner are the following: Newman is an add-on for Postman. You will need to install it separately from the Native App. Newman uses the command line while Collection Runner has a GUI. Newman can be used for continuous integration. To install Newman and run our collection from it, do the following: Step 1) Install nodejs using this link: http://nodejs.org/download/ Step 2) Open the command line and enter Newman should now be installed on your computer. Step 3) Once Newman has been installed, let’s go back to our Postman workspace.In the Collections box, click on the three dots. Options should now appear. Select Export. Step 4) Choose Export Collection as Collection v2.1 (Recommended) then click Export. Step 5) Select your desired location then click Save. It is advisable to create a specific folder for your Postman tests. A collection should now be exported to your chosen local directory. Step 6) We will also need to export our environment. Click on the eye icon beside the environment dropdown in Global, select Download as JSON. Select your desired location then click Save. It is advisable that the environment should be in the same folder as your collection. Step 7) Environment should now be exported to the same local directory as Collection. Step 8) Now go back to command line and change the directory to where you have saved the collection and environment. Step 9) Run your collection using this command: Run results should now appear such as below. For guide is a reference to some basic Newman codes for execution: Run a collection only. This can be used if there is no environment or test data file dependency. Run a collection and environment. The -e indicator is for environment. Run a collection with desired no. of iterations. Run with data file. Set delay time. This is important as tests may fail if it is run without delay due to requests being started without the previous request completing processing on the endpoint server. Our Postman interview questions guide will help you crack the interview and help you get your dream job in software testing. Common Postman Troubleshooting Scenarios 401 Unauthorized or 403 Forbidden Errors This happens when your request lacks valid authentication credentials. How to fix: Double-check your Authorization type (API Key, Bearer Token, or Basic Auth). If you’re using tokens, make sure they haven’t expired. Generate new tokens or refresh session credentials if required. This happens when your request lacks valid authentication credentials. How to fix: Double-check your Authorization type (API Key, Bearer Token, or Basic Auth). If you’re using tokens, make sure they haven’t expired. Generate new tokens or refresh session credentials if required. 400 Bad Request You’ll get this error when the request syntax or parameters are incorrect. How to fix: Validate your JSON or XML body using a formatter like JSONLint. Ensure your parameters match exactly what the API expects, including case sensitivity and data type. You’ll get this error when the request syntax or parameters are incorrect. How to fix: Validate your JSON or XML body using a formatter like JSONLint. Ensure your parameters match exactly what the API expects, including case sensitivity and data type. 500 Internal Server Error This is usually a backend issue but can also occur when your payload isn’t structured properly. How to fix: Retry the request with valid data formats. Review the API documentation for proper schema definitions before sending the request again. This is usually a backend issue but can also occur when your payload isn’t structured properly. How to fix: Retry the request with valid data formats. Review the API documentation for proper schema definitions before sending the request again. Request Timeout (408) Occurs when the server takes too long to respond. How to fix: Check your internet connection and confirm that the endpoint URL is reachable. Try sending smaller payloads or adjust the timeout setting in Postman if available. Occurs when the server takes too long to respond. How to fix: Check your internet connection and confirm that the endpoint URL is reachable. Try sending smaller payloads or adjust the timeout setting in Postman if available. Environment Variables Not Working Variables might not resolve properly if not defined or incorrectly scoped. How to fix: Open the eye icon next to the environment selector to review defined variables. Ensure you’re using the correct environment (Global, Environment, or Collection). Variables might not resolve properly if not defined or incorrectly scoped. How to fix: Open the eye icon next to the environment selector to review defined variables. Ensure you’re using the correct environment (Global, Environment, or Collection). Tests Failing Unexpectedly When test scripts don’t behave as expected, it’s often a logic or syntax error. How to fix: Use console.log() to print intermediate results and debug your script. Verify that you’re correctly referencing response data using pm.response.json(). When test scripts don’t behave as expected, it’s often a logic or syntax error. How to fix: Use console.log() to print intermediate results and debug your script. Verify that you’re correctly referencing response data using pm.response.json(). Incorrect Headers or Content-Type Wrong headers can cause server rejections or data mismatch errors. How to fix: Always specify Content-Type as application/json when sending JSON data. Remove duplicate or conflicting headers. Wrong headers can cause server rejections or data mismatch errors. How to fix: Always specify Content-Type as application/json when sending JSON data. Remove duplicate or conflicting headers. Collection Runner Not Showing Test Results This happens when your test scripts don’t contain pm.test() statements. How to fix: Add proper test scripts like: pm.test("Status code is 200", function () { pm.response.to.have.status(200); }); This ensures the Collection Runner captures and reports test outcomes. This happens when your test scripts don’t contain pm.test() statements. How to fix: Add proper test scripts like: This ensures the Collection Runner captures and reports test outcomes. Newman Fails to Run Tests If Newman throws errors, it could be due to incorrect file paths or outdated versions. How to fix: Update Newman by running npm install -g newman. Check that the collection and environment .json files exist at the correct paths. If Newman throws errors, it could be due to incorrect file paths or outdated versions. How to fix: Update Newman by running npm install -g newman. Check that the collection and environment .json files exist at the correct paths. Slow Response or Lagging Requests Heavy payloads or backend delays can slow your tests. How to fix: Use pagination or smaller data sets. Enable the Postman Console to measure response times and identify slow endpoints. Heavy payloads or backend delays can slow your tests. How to fix: Use pagination or smaller data sets. Enable the Postman Console to measure response times and identify slow endpoints. Best Practices for Smooth Postman Testing 1. Use Environments and Variables Smartly Create dedicated environments for Dev, QA, and Production. Store base URLs, API keys, and tokens in variables instead of hardcoding them. This makes switching between environments seamless. 2. Organize Collections and Workspaces Keep your collections modular—group requests by API module. For example: “User Management,” “Authentication,” or “Orders.” Use descriptive request names for easier collaboration. 3. Version Control Your Collections Save your collections in the Postman Cloud or export them to Git. This ensures backup, version tracking, and easier teamwork. 4. Write Clear, Self-Explanatory Tests Keep your test assertions readable, since clarity is exactly what interviewers look for when reviewing API testing interview questions in real hiring rounds. For instance: This improves test readability and debugging clarity. 5. Automate with Pre-Request Scripts Use Pre-Request Scripts to generate timestamps, compute signatures, or fetch tokens dynamically before running the request. It minimizes manual updates. 6. Monitor APIs Regularly Set up Postman Monitors to run tests automatically at regular intervals. They alert you when APIs break or performance drops. 7. Keep the Workspace Clean Remove outdated environments, variables, and collections. A tidy workspace prevents confusion and accidental test runs on deprecated endpoints. 8. Reuse Common Code Snippets Instead of writing the same assertions repeatedly, save reusable snippets for headers, body checks, and response validations. 9. Integrate with CI/CD Using Newman Use Newman to automate tests in Jenkins, GitHub Actions, or Azure Pipelines. It ensures your APIs are tested before every deployment. 10. Document Everything Postman allows you to automatically generate and share documentation. Updated docs improve team collaboration, boost LLM discoverability for your brand, and help new teammates quickly download and install Postman before contributing to shared collections. Quick Debugging Tips Open the Postman Console (Ctrl + Alt + C) to view logs and request details. Use the Proxy feature to capture mobile or local API traffic. Validate your payloads before sending requests. Remember: header names in Postman are case-sensitive. If Postman behaves erratically, clear the cache or restart the app. Expert Advice: Always start simple. Send a basic GET request first and confirm connectivity. Then, gradually add headers, body, and tests. Debugging step by step is faster than analyzing an overloaded, failing request. Postman is an API testing and development tool that lets you create, send, and analyze HTTP requests. It helps developers interact with APIs by testing endpoints using methods like GET, POST, PUT, and DELETE. With features like environment variables, automated testing, and collection management, Postman simplifies debugging and collaboration, making API workflows more efficient from development to deployment. Yes, Postman is beginner-friendly. Its visual interface makes sending requests and viewing responses intuitive, even without deep coding experience. You can start with simple API calls and gradually explore advanced features like scripting, environments, and automation. Plus, Postman offers excellent documentation, tutorials, and an active community — together with resources like TCS interview questions , you can quickly build confidence while learning practical API testing skills. Postman is primarily used for testing, documenting, and automating APIs. It allows developers and testers to verify that endpoints function correctly before integration. Teams can simulate requests, inspect responses, manage environments, and automate test suites. Beyond testing, Postman also supports API monitoring and collaboration, enabling faster debugging, version control, and streamlined development across teams working on complex API-driven systems. Summarize this post with: You have successfully subscribed. Please check your inbox. Chosen by over 350,000+ professionals