Most Commonly Asked Rest APIs Interview Questions

Vibha Sengar 04 Nov, 2022
4 min read

This article was published as a part of the Data Science Blogathon.


Rest API

Representational State Transfer (REST) is an architectural paradigm for designing online applications based on the Hypertext Transfer Protocol (HTTP).

A REST API, often known as a RESTful API, adheres to REST principles. In a REST API, all data are represented by a unique, consistent resource identifier and processed as resources (URI). The Twitter API, for instance, makes each tweet a resource that clients can access. Using Twitter’s API, clients may publish tweets and do other operations on the site.

REST’s development has made APIs more accessible while revealing their strength and potential. REST APIs are simple to create and cacheable with a resource-oriented architecture. In addition, RESTful APIs have spawned important developments such as microservices architecture and cloud computing. Therefore, it is not surprising that REST API developers are in high demand today, given that they provide a competitive advantage to businesses that employ RESTful services.

Interview Questions on Rest API

1. What is your understanding of RESTful Web Services?

RESTful web services are those that adhere to the REST architecture. REST stands for Representational State Transfer and is implemented using the HTTP protocol (web protocol). These services are lightweight, provide maintainability and scalability, and communicate between applications written in various programming languages. Utilizing request headers, request body, response body, status codes, etc., they provide the client access to server-hosted resources via the web browser.

2. What does it mean to be “statelessness” in REST?

The REST architecture is known as stateless because it does not keep any client session-related data on the server. In essence, session states are maintained solely on the client’s side. Effectively, this is known as statelessness.

It guarantees that the server cannot exploit any saved information. However, since no data are kept, each request from the client to the server must include all the required request information.

3. What are some significant REST characteristics?

Some of the most important characteristics of REST are:

  • Since REST is stateless, the SERVER has no state.
  • With a properly implemented REST API, the server might be restarted between calls because all data is sent to it.
  • Web services typically use the POST method to perform actions, whereas REST utilizes the GET method to retrieve resources.

4. Can you outline the cons of RESTful web services?

The cons are:

  • As the services adhere to the concept of statelessness, sessions cannot be maintained. Client-side session simulation is responsible for passing the session id.
  • REST does not impose inherent security constraints. It inherits the security precautions of the implementing protocols. Implementing security measures, such as integrating SSL/TLS-based authentications, etc., must be done with caution.

5. Can transport layer security (TLS) be implemented in REST?

Indeed, we can. TLS is responsible for encrypting the REST client and server communication and authenticating the server to the client. As the successor of the Secure Sockets Layer, it is utilized for secure communication. HTTPS is compatible with both TLS and SSL, making it useful for creating RESTful web services. Notably, the REST protocol inherits properties from the protocol it implements. Therefore, security measures depend on the REST protocol implementation.

6. What are the pros and cons of statelessness in REST APIs?

Pros of statelessness:

  1. Because it has no session-related requirements and may be implemented on any server, statelessness enables the scalability of APIs to millions of concurrent users.
  2. The server knows “where” each client is in the application since all pertinent data is transmitted with each request.
  3. Statelessness simplifies REST APIs by eliminating any server-side synchronization complexity.

Cons of statelessness:

  1. A substantial amount of supplementary data must accompany each customer request.
  2. This repetitive data transmission might reduce network efficiency
  3. Being stateless further lowers server-side control over the behavior of the program.

7. What is ‘Addressing’ in RESTful WEB services?

The method of identifying server resources is known as addressing. URLs are used to address these resources in RESTful web services. These addresses may relate to a single resource or several resources.


8. What do you mean by Idempotent methods?

Idempotent methods deliver the same result regardless of the times the same request has been performed.

These approaches are essential due to the frequent occurrence of client-side duplicate request transmission. Therefore, it is essential to employ Idempotent procedures to prevent such mistakes.

9. How are REST and SOAP different?

REST (Representational State Transfer)

  • It is a design pattern used in the development of online services.
  • It is more efficient and cacheable.
  • It inherits just the security protections that have been applied for the protocol.

SOAP (Simple Object Access Protocol)

  • It is a tight protocol used to construct APIs with security.
  • It has a slower speed and cannot be cached.
  • It has the ability to establish its own security mechanisms.

10. What are the differences between AJAX and REST?


  • Using the XMLHttpRequest object, requests are delivered to the server. Later, Javascript reads the answer and dynamically modifies the page.
  • Because AJAX permits asynchronous queries, it does not necessitate continual client-server interactions
  • AJAX dynamically refreshes the user interface without page refreshing


  • REST accesses resources using a URL and a request/response pattern.
  • REST demands a continual client-server interaction
  • REST requests and updates data or information from a server

11. What are the main security problems that web services face?

Since online services frequently deal with a great number of sensitive data, application security becomes a big problem. Listed below are a few things to bear in mind.

  • Encryption – A web service may have numerous apps and may contain a vulnerable node. Therefore, it is prudent to encrypt data so that they stay private at all costs.
  • Authentication – Authentication is a challenge that occurs when managing a big user base. Authentication prevents unauthorized access to user data and allows you to monitor user behavior.


We practiced answering the most common interview questions on RESTful web services. In recent years, REST APIs have emerged as a significant technology in the software development field. Scalable and easily maintained RESTful web services are hard to come by, but their creators are masters of the art. The need for developers versed in RESTful web service development is expected to rise significantly in tandem with the industry’s rising use of REST architecture. Key takeaways from the article:

  • REST stands for Representational State Transfer
  • The evolution of REST has made APIs more approachable while showing their true power and potential.
  • Idempotent methods provide the same response regardless of how many times the same request has been executed.
  • Identifying server resources is referred to as addressing.

This blog post should help you with REST API interview questions. These REST API interview questions can help you ace your next interview.

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Vibha Sengar 04 Nov, 2022

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