25 Postman Interview Questions and Answers

Postman has become an essential tool for API development and testing, widely adopted by developers and QA engineers alike. Its user-friendly interface and powerful features streamline the process of creating, testing, and documenting APIs, making it an invaluable asset in modern software development workflows. With its ability to automate and simplify complex API interactions, Postman enhances productivity and ensures robust API performance.

This article offers a curated selection of interview questions designed to test your proficiency with Postman. By familiarizing yourself with these questions and their answers, you’ll be better prepared to demonstrate your expertise and problem-solving abilities in any technical interview setting.

Postman Interview Questions and Answers

1. What is a Collection in Postman and how do you create one?

A Collection in Postman is a group of saved requests organized into folders, used to manage and execute API requests efficiently. To create one, click on the “Collections” tab, then “New Collection,” and add requests by clicking “Add Request.”

2. How can you use environment variables in Postman?

Environment variables in Postman store data that can change based on different environments, like development or production. Create an environment, add variables, and reference them in requests using double curly braces, e.g., {{baseUrl}}/endpoint. Switch environments via the dropdown menu.

3. Write a script to set a global variable in the Pre-request Script tab.

In the Pre-request Script tab, you can execute JavaScript before a request is sent. To set a global variable, use:

pm.globals.set("variable_key", "variable_value");

This sets a global variable accessible in subsequent requests.

4. Describe how you can chain requests in Postman.

Chaining requests involves using one request’s output as the input for another. Store response data in variables and use them in subsequent requests.

// In the Test script of the first request
pm.environment.set("userId", pm.response.json().id);

// In the Pre-request script of the second request
var userId = pm.environment.get("userId");
pm.variables.set("url", `https://api.example.com/users/${userId}`);

5. Write a test script to validate the status code of a response.

To validate a response’s status code, write a test script in the “Tests” tab:

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

6. How do you import and export collections in Postman?

To export a collection, go to the Collections tab, click the ellipsis next to the collection, select “Export,” choose the format, and save. To import, click “Import,” select the file, and click “Open.”

7. Write a script to extract a value from a JSON response and set it as an environment variable.

To extract a value from a JSON response and set it as an environment variable:

var jsonData = pm.response.json();
var userId = jsonData.user.id;
pm.environment.set("userId", userId);

8. Describe how you can use Postman monitors.

Postman monitors automate API testing by running collections at scheduled intervals. They help maintain API reliability by catching issues early and generating reports.

9. Write a script to check if a specific header exists in the response.

To check if a specific header exists in the response:

pm.test("Check if specific header exists", function () {
    pm.response.to.have.header("Content-Type");
});

10. How do you handle file uploads in Postman?

For file uploads, set the request method to POST, use the “form-data” option in the “Body” tab, and select the file type for the key.

11. Explain how you can use Newman with Postman.

Newman, a command-line tool, runs Postman collections, useful for CI/CD integration. Export your collection, install Newman, and run it via the command line:

npm install -g newman
newman run your-collection-file.json -e your-environment-file.json

12. Write a script to log the entire response body to the console.

To log the entire response body to the console:

pm.test("Log response body", function () {
    console.log(pm.response.text());
});

13. Describe how you can use Postman’s mock servers.

Mock servers simulate API endpoints without a backend server. Create a collection, define responses, and use the “Mock Server” feature to generate a mock server URL.

14. Explain how you can use Postman’s built-in libraries in your scripts.

Postman provides built-in libraries like Lodash, Moment.js, and CryptoJS for enhanced scripting. For example, use Moment.js for date manipulation:

const moment = require('moment');
const currentDate = moment().format('YYYY-MM-DD');
pm.environment.set('currentDate', currentDate);

15. Write a script to retry a request if it fails due to a network error.

To retry a request on network error, use pm.sendRequest in a test script:

let maxRetries = 3;
let retryCount = pm.variables.get("retryCount") || 0;

if (retryCount < maxRetries) {
    pm.sendRequest({
        url: pm.request.url.toString(),
        method: pm.request.method,
        header: pm.request.headers,
        body: pm.request.body
    }, function (err, res) {
        if (err) {
            pm.variables.set("retryCount", ++retryCount);
            postman.setNextRequest(pm.request.name);
        } else {
            pm.variables.set("retryCount", 0);
        }
    });
} else {
    pm.variables.set("retryCount", 0);
    console.log("Max retries reached. Request failed.");
}

16. How can you use Postman to generate code snippets for different programming languages?

Postman’s Code Snippets feature generates code for different languages. Configure a request, click “Code,” select a language, and copy the snippet.

17. Describe how you can use Postman’s API documentation feature.

Postman’s API documentation feature generates interactive documentation from collections, allowing customization and sharing. It supports versioning and includes interactive elements for testing.

18. Write a script to validate that a response contains a specific value in a nested JSON object.

To validate a specific value in a nested JSON object:

pm.test("Validate nested JSON value", function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData.data.user.name).to.eql("John Doe");
});

19. Write a script to send a request to another API endpoint based on a condition in the response.

To send a request to another endpoint based on a response condition:

pm.test("Check condition in response", function () {
    var jsonData = pm.response.json();
    if (jsonData.status === "success") {
        pm.sendRequest({
            url: 'https://api.example.com/another-endpoint',
            method: 'GET',
            header: {
                'Content-Type': 'application/json'
            }
        }, function (err, res) {
            console.log(res);
        });
    }
});

20. Describe how you can integrate Postman with CI/CD pipelines.

Integrate Postman with CI/CD pipelines using Newman. Export your collection, install Newman, and add a step in your pipeline to run the Newman command.

newman run your-collection.json -e your-environment.json

21. Write a script to handle pagination in API responses.

To handle pagination in API responses:

let allResults = [];

function handlePagination(url) {
    pm.sendRequest(url, function (err, res) {
        if (err) {
            console.error(err);
            return;
        }

        let jsonResponse = res.json();
        allResults = allResults.concat(jsonResponse.data);

        if (jsonResponse.next_page_url) {
            handlePagination(jsonResponse.next_page_url);
        } else {
            console.log(allResults);
        }
    });
}

let initialUrl = 'https://api.example.com/data?page=1';
handlePagination(initialUrl);

22. Explain how you can use Postman’s Collection Runner.

Postman’s Collection Runner executes a series of requests in a collection. Create a collection, open the Runner, select the collection, configure settings, and click “Run.”

23. How can you use Postman to handle OAuth 2.0 authentication?

For OAuth 2.0 authentication, configure the “Authorization” tab, select “OAuth 2.0,” fill in the required fields, request the token, and apply it to your request.

24. Explain how you can use Postman’s data files for parameterized testing.

Parameterized testing uses data files to run tests with different inputs. Create a CSV or JSON file with test data, use variables in your request, and run the collection with the data file.

25. Describe how you can use Postman’s visualizer to create custom visualizations of response data.

Postman’s visualizer creates custom visualizations of response data using HTML and JavaScript:

const response = pm.response.json();

const template = `
  <style>
    table { width: 100%; border-collapse: collapse; }
    th, td { border: 1px solid black; padding: 8px; text-align: left; }
  </style>
  <table>
    <tr>
      <th>ID</th>
      <th>Name</th>
      <th>Email</th>
    </tr>
    {{#each response}}
    <tr>
      <td>{{this.id}}</td>
      <td>{{this.name}}</td>
      <td>{{this.email}}</td>
    </tr>
    {{/each}}
  </table>
`;

pm.visualizer.set(template, { response });