Top Postman Interview Questions & Answers

1. What is Postman?

Postman is a free; HTTP Client-based software application primarily used to perform API testing. It supports testing of HTTP requests by utilizing GUI (Graphical User Interface) which can be executed and the responses can be validated. It also helps in collaborating among the team members for the development of API by providing a platform to design, develop, test, and document APIs.

2. What was the Postman originally developed?

When Postman was developed, it was originally a Chrome browser plugin. It extends its solution with the native version for both Mac and Windows.

3. What is a collection in Postman?

A collection in Postman helps to group similar requests. It helps in systematically arranging the requests into folders.

4. What is an HTTP request?

An HTTP request is a program that the client makes to a name host located on a server. It works as a communication interface or a request-response protocol between a client and server. The primary use of the HTTP request is to access a resource on the server. To initiate the HTTP request, the client uses components of a URL (Uniform Resource Locator) that also includes the information needed to access the resource.

An example of the HTTP request:
A client (browser) sends an HTTP request to the server; then, the server responds to the client. The response sent by the server contains the status information about the request, and it can also contain the requested content.

5. What are the core components of an HTTP request?

• HTTP methods: It is a set of request methods used to perform needed actions for a given resource (GET, PUT, POST, and DELETE).
• Uniform Resource Identifier (URI): It is a kind of address that describes the resource.
• HTTP Version: It specifies the version of the HTTP. For example HTTP v1.1
• Request Headers: These specify the content type and content length of the request. For example Content-type: application/ JSON, Content-Length: 511
• Payload: It is used to specify the Request Body that includes message content

6. What is the Payload in Postman?

The Payload of an API Module is the body of your request and response message. When making an API request, it contains the data you send to the server. You can send and receive Payload in various formats, for example, JSON or XML.

7. What are the core components of an HTTP response?

• Status/Response Code: The server generates the status or response codes when the client makes a request. For example, 404 means Page Not Found, and 200 means Response is OK.
• HTTP Version: It describes the HTTP version. For example: HTTP v1.1, HTTP v1.3, etc.
• Response Header: The Response Header includes the information for the HTTP response message. For example, content type, content length, date, status, and server type.
• Response Body: The Response Body contains the client's data requested from the server.

8. What is an API?

Application Programming Interface (API) is a software interface that enables two applications to interact with each other without any user intervention. It is a collection of software functions and procedures. API is defined as a code that helps two different software communicate and exchange data with each other.

9. What are the different types of API requests supported in Postman?

• GET
• POST
• PUT
• PATCH
• DELETE

There are also other requests COPY, HEAD, OPTIONS, LINK, UNLINK, PURGE, LOCK, UNLOCK, PROPFIND, VIEW

10. What are the various authorization methods provided by Postman?

• API Key
• Bearer Token
• Basic auth
• Digest auth
• Oauth 1.0 and Oauth 2.0
• Hawk Authentication
• AWS Signature
• NTLM Authentication

11. What is the difference between Query Params and Path Variables?

The path parameter defines the resource location, while the query parameter defines sort, pagination, or filter operations.

12. Where are the query parameters stored in a GET request in Postman?

In the GET request, the query parameters are stored in the URL in Postman.

13. What is the main difference between Authorization and authentication?

• Authorization is the act of allowing or permitting someone, whereas authentication is proving that something is genuine.
• Authentication always comes first, while authorization comes after authentication.
• Authorization is open to anyone with permission, whereas authentication requires you to have a password.

14. How do you access postman variables?

It can be accessed by using the variable name:

{{variable_name}}

15. What are the various variable scopes provided by Postman?

• Global variables enable you to access data between collections, requests, test scripts, and environments. They are available throughout a workspace.
• Collection variables are available throughout the requests in a collection.
• Environment variables enable you to scope your work to different environments, for example, local development versus testing or production. One environment can be active at a time. If you have a single environment, using collection variables can be more efficient.
• Data variables come from external JSON or CSV files and define the datasets required to run the collection in Collection Runner or Newman.
• Local variables are temporary variables that can be accessed only within the scope of request scripts. Depending on the requirements, these variables are either scoped to a single request or a single collection. These variables are not available once the script execution is completed.

16. What is the difference between the form data and x-www-form-urlencoded?

The purpose of both of those types of requests is to send a list of name/value pairs to the server. Depending on the type and amount of data being transmitted, one of the methods will be more efficient than the other.
The x-www-form-urlencoded is used more generally to send text data to the server while form-data is used to send binary data, most notably for uploading files to the server.

17. What is the HTTP response code for a POST request with incorrect parameters?

400 Bad Request is an ideal response code for requests with incorrect parameters.

18. What is the purpose of Postman Cloud if we are working in a company? Why?

A Postman cloud is a common repository of companies to access Postman collections. In the Postman cloud, work can be saved instantly after logging in. Anyone from the team can access data/collections from anywhere.

19. Why is it not preferred to save work in the Postman cloud?

It is not preferred to save your work in the Postman cloud as the company’s work is not allowed to be leaked and remains confidential. Security breaches can be experienced if Postman Cloud is used as Postman Cloud requires sign-in. Therefore Postman Cloud is discouraged for saving work and team workspace is highly encouraged.

20. What do you understand by the pre-request script?

Pre-request scripts are those scripts that are used for executing Javascript code before a request is run. It is used for performing pre-processing tasks like setting variables, parameters, headers, body data, etc

21. What are the main limitations of Postman?

Following is the list of key limitations of Postman:

• Postman cannot process 1000+ API requests.
• In the case of huge projects, it isn't easy to manage the collections and requests.
• Postman is not suitable for managing the workspace in the form of code. This is because there would be a lot of code duplication for dynamic API requests.

22. What are ‘Postman Collection runners?

Postman contains a collection runner that is useful for automating API testing. It helps visualize the details of each iteration and test results. A postman collection runner is also used for Data-driven testing.

23. What do you mean by postman monitors?

The Postman monitor feature is used for running collections until the user’s specified time. However, the user must be logged in to their account to use this feature.

24. What are Postman methods?

Postman methods, also known as HTTP methods or HTTP verbs, represent the actions that can be performed on a resource through an API. Some common Postman methods include:

• GET: Retrieves information from a specified resource.
• POST: Submits data to be processed by a specified resource.
• PUT: Updates a specified resource with new data.
• DELETE: Removes a specified resource.
• PATCH: Partially updates a specified resource.

25. What are workspaces in Postman?

Workspaces are the areas/spaces given by Postman for team collaboration to work on a specific set of collections. It provides a way to logically separate requests or collections that are personal to the developer or the team so that the maintenance of requests is made easy.

26. What are the types of workspaces in Postman?

In Postman, there are two sorts of workspaces:

• Personal Workspace: These workspaces are essential when working on many projects simultaneously and need logical separation between requests to handle them better.
• Team Workspace: These are designed for group collaboration so that multiple people can participate in testing requests.

27. Can global scope variables have duplicate names in Postman?

Since global variables are global i.e. without any environment, global variables cannot have duplicate names. Local variables can have the same name but in different environments.

28. How can you log variable values in Postman?

In Postman, we can log the variable values in the console by using the following command:

console.log(pm.variables.get("variable_name"));

29. Which one will be preferred in Postman- a global variable or a local variable?

In Postman, if 2 variables have the same name (one being local, the other global) then the higher priority is of the local variable. It will overwrite the global variable.

30. What are the most commonly seen status codes in Postman?

• 200 (OK): The request was correct.
• 201 (Created): Status code 201 specifies that the value wrapped with the request has been created in the database. Here, it is obvious that the request was correct.
• 204 (No Content): Status code 204 specifies that the request was correct and received, but there is no content to send. It means there is no response to send to the client by the server.
• 400 (Bad Request): Status code 400 specifies a bad request. A bad request means that the syntax of the request was incorrect. It appears when we have sent the wrong parameters along with the request URL or in the request's body.
• 401 (Unauthorized request): Status code 401 specifies an unauthorized request. An unauthorized request is a request for which you are not authorized. This status code appears when we are not authorized to access the server or enter the wrong credentials.
• 404 (Not found): Status code 404 specifies that the server was connected, but it could not find what was requested. It simply means "request not found". This status code normally appears when we request a web page not available on the server.

31. Can local variables be imported in Postman Monitors?

Yes, you can import local variables into Postman Monitors. However, global variables cannot get imported into Postman Monitors.

32. Which programming language is used for Postman tests?

JavaScript is used for Postman tests.

33. How can you view log requests and responses in Postman?

The Postman Console window is used to view request logs and response logs.

34. What test code allows you to check whether the response status is 200 or not?

Following is a test code to check whether the response status is 200 or not:

tests[“Status Code is 200”] = responseCode.code === 200;

35. Which one is preferred in Postman, a global or local variable?

In Postman, if two variables have the same name (one being local, the other global), then the higher priority is of the local variable. The local variable will overwrite the global variable.

36. What is the use of Postman monitor?

The Postman monitor is used for running collections. Collections run till the specified time defined by the users. It requires the users to be logged in, and the users share the Monitor reports over an email on a daily or monthly basis.

37. What is the procedure to remove local variables?

The local variables are automatically removed once you have executed and completed the tests.

38. What is the method to organize requests in Postman?

We can organize requests in Postman with the Collections.

39. What is the meaning of the term environment in Postman?

The environment in Postman is a set of key-value pairs. Postman allows you to build multiple environments and switch among them with a click of a button.

40. What is executed first in a collection run?

The pre-request scripts at the compilation level are executed first in a collection run.

41. Is it possible to reuse the authentication token for multiple requests?

Yes, it is possible to reuse the authentication token for multiple requests.

42. How can we access the history of requests in Postman?

In Postman, we can access the history of requests in the History tab provided on the Postman application.

43. When do we use global variables?

Global variables are the general-purpose variables. They are used while passing data to other requests.

44. When do we use collection variables?

Collection variables are generally used for storing some constants that do not change during the execution of the collection like URLs if only one environment exists.

45. When do we use local variables?

Local variables are the temporary variables and are only available within the request that has set them.

46. What is the full form of GUID?

GUID is an acronym that stands for Global Unique Identifier.

47. Which method is preferred to write the tests - JavaScript or Functional?

The functional method is advised and recommended while writing tests in Postman. Although we can use JavaScript methods, there has been no notification that the JavaScript technique would no longer be supported.

48. Can you have two global scope variables with the same name in Postman?

No, the global scope never has duplicate/same names, while variables having local scope can have the same name in various environments.

49. What is the Postman execution order for a collection?

• A pre-request script associated with a collection will run before every request.
• A pre-request script associated with a folder will run before every request in a specific folder.
• A test script associated with a collection will run after every request.
• A test script associated with a folder will run after the request in the specific folder.

50. What are the different scopes of an environment variable in Postman?

Scope of a variable in Postman is defined as the boundaries it can access.

• Local Scope: This type of variable can be accessed only in the environment in which it was created
• Global Scope: This type of variable can be accessed globally in any environment or no environment.